diff options
| -rw-r--r-- | ChangeLog | 21 | ||||
| -rw-r--r-- | Makefile.in | 6 | ||||
| -rw-r--r-- | auth.h | 6 | ||||
| -rw-r--r-- | auth2-jpake.c | 557 | ||||
| -rw-r--r-- | auth2.c | 12 | ||||
| -rw-r--r-- | jpake.c | 604 | ||||
| -rw-r--r-- | jpake.h | 134 | ||||
| -rw-r--r-- | monitor.c | 227 | ||||
| -rw-r--r-- | monitor.h | 9 | ||||
| -rw-r--r-- | monitor_wrap.c | 167 | ||||
| -rw-r--r-- | monitor_wrap.h | 22 | ||||
| -rw-r--r-- | readconf.c | 18 | ||||
| -rw-r--r-- | readconf.h | 3 | ||||
| -rw-r--r-- | schnorr.c | 407 | ||||
| -rw-r--r-- | servconf.c | 20 | ||||
| -rw-r--r-- | servconf.h | 4 | ||||
| -rw-r--r-- | ssh2.h | 9 | ||||
| -rw-r--r-- | ssh_config.5 | 15 | ||||
| -rw-r--r-- | sshconnect2.c | 303 | ||||
| -rw-r--r-- | sshd_config.5 | 18 |
20 files changed, 2537 insertions, 25 deletions
@@ -7,6 +7,25 @@ [auth.c] need unistd.h for close() prototype (ID sync only) + - djm@cvs.openbsd.org 2008/11/04 08:22:13 + [auth.h auth2.c monitor.c monitor.h monitor_wrap.c monitor_wrap.h] + [readconf.c readconf.h servconf.c servconf.h ssh2.h ssh_config.5] + [sshconnect2.c sshd_config.5 jpake.c jpake.h schnorr.c auth2-jpake.c] + [Makefile.in] + Add support for an experimental zero-knowledge password authentication + method using the J-PAKE protocol described in F. Hao, P. Ryan, + "Password Authenticated Key Exchange by Juggling", 16th Workshop on + Security Protocols, Cambridge, April 2008. + + This method allows password-based authentication without exposing + the password to the server. Instead, the client and server exchange + cryptographic proofs to demonstrate of knowledge of the password while + revealing nothing useful to an attacker or compromised endpoint. + + This is experimental, work-in-progress code and is presently + compiled-time disabled (turn on -DJPAKE in Makefile.inc). + + "just commit it. It isn't too intrusive." deraadt@ 20081103 - OpenBSD CVS Sync @@ -4857,4 +4876,4 @@ OpenServer 6 and add osr5bigcrypt support so when someone migrates passwords between UnixWare and OpenServer they will still work. OK dtucker@ -$Id: ChangeLog,v 1.5129 2008/11/05 05:12:54 djm Exp $ +$Id: ChangeLog,v 1.5130 2008/11/05 05:20:46 djm Exp $ diff --git a/Makefile.in b/Makefile.in index c1b7ab5a..312b8d2b 100644 --- a/Makefile.in +++ b/Makefile.in @@ -1,4 +1,4 @@ -# $Id: Makefile.in,v 1.297 2008/07/08 14:21:12 djm Exp $ +# $Id: Makefile.in,v 1.298 2008/11/05 05:20:46 djm Exp $ # uncomment if you run a non bourne compatable shell. Ie. csh #SHELL = @SH@ @@ -71,7 +71,7 @@ LIBSSH_OBJS=acss.o authfd.o authfile.o bufaux.o bufbn.o buffer.o \ atomicio.o key.o dispatch.o kex.o mac.o uidswap.o uuencode.o misc.o \ monitor_fdpass.o rijndael.o ssh-dss.o ssh-rsa.o dh.o kexdh.o \ kexgex.o kexdhc.o kexgexc.o scard.o msg.o progressmeter.o dns.o \ - entropy.o scard-opensc.o gss-genr.o umac.o + entropy.o scard-opensc.o gss-genr.o umac.o jpake.o schnorr.o SSHOBJS= ssh.o readconf.o clientloop.o sshtty.o \ sshconnect.o sshconnect1.o sshconnect2.o mux.o @@ -81,7 +81,7 @@ SSHDOBJS=sshd.o auth-rhosts.o auth-passwd.o auth-rsa.o auth-rh-rsa.o \ auth.o auth1.o auth2.o auth-options.o session.o \ auth-chall.o auth2-chall.o groupaccess.o \ auth-skey.o auth-bsdauth.o auth2-hostbased.o auth2-kbdint.o \ - auth2-none.o auth2-passwd.o auth2-pubkey.o \ + auth2-none.o auth2-passwd.o auth2-pubkey.o auth2-jpake.o \ monitor_mm.o monitor.o monitor_wrap.o kexdhs.o kexgexs.o \ auth-krb5.o \ auth2-gss.o gss-serv.o gss-serv-krb5.o \ @@ -1,4 +1,4 @@ -/* $OpenBSD: auth.h,v 1.61 2008/07/02 12:03:51 dtucker Exp $ */ +/* $OpenBSD: auth.h,v 1.62 2008/11/04 08:22:12 djm Exp $ */ /* * Copyright (c) 2000 Markus Friedl. All rights reserved. @@ -59,6 +59,7 @@ struct Authctxt { struct passwd *pw; /* set if 'valid' */ char *style; void *kbdintctxt; + void *jpake_ctx; #ifdef BSD_AUTH auth_session_t *as; #endif @@ -156,6 +157,9 @@ int bsdauth_respond(void *, u_int, char **); int skey_query(void *, char **, char **, u_int *, char ***, u_int **); int skey_respond(void *, u_int, char **); +void auth2_jpake_get_pwdata(Authctxt *, BIGNUM **, char **, char **); +void auth2_jpake_stop(Authctxt *); + int allowed_user(struct passwd *); struct passwd * getpwnamallow(const char *user); diff --git a/auth2-jpake.c b/auth2-jpake.c new file mode 100644 index 00000000..0029ec26 --- /dev/null +++ b/auth2-jpake.c @@ -0,0 +1,557 @@ +/* $OpenBSD: auth2-jpake.c,v 1.1 2008/11/04 08:22:12 djm Exp $ */ +/* + * Copyright (c) 2008 Damien Miller. All rights reserved. + * + * Permission to use, copy, modify, and distribute this software for any + * purpose with or without fee is hereby granted, provided that the above + * copyright notice and this permission notice appear in all copies. + * + * THE SOFTWARE IS PROVIDED "AS IS" AND THE AUTHOR DISCLAIMS ALL WARRANTIES + * WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF + * MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR + * ANY SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES + * WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR PROFITS, WHETHER IN AN + * ACTION OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING OUT OF + * OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE. + */ + +/* + * Server side of zero-knowledge password auth using J-PAKE protocol + * as described in: + * + * F. Hao, P. Ryan, "Password Authenticated Key Exchange by Juggling", + * 16th Workshop on Security Protocols, Cambridge, April 2008 + * + * http://grouper.ieee.org/groups/1363/Research/contributions/hao-ryan-2008.pdf + */ + +#include <sys/types.h> +#include <sys/param.h> + +#include <pwd.h> +#include <stdio.h> +#include <string.h> +#include <login_cap.h> + +#include <openssl/bn.h> +#include <openssl/evp.h> + +#include "xmalloc.h" +#include "ssh2.h" +#include "key.h" +#include "hostfile.h" +#include "buffer.h" +#include "auth.h" +#include "packet.h" +#include "dispatch.h" +#include "log.h" +#include "servconf.h" +#include "auth-options.h" +#include "canohost.h" +#ifdef GSSAPI +#include "ssh-gss.h" +#endif +#include "monitor_wrap.h" + +#include "jpake.h" + +#ifdef JPAKE + +/* + * XXX options->permit_empty_passwd (at the moment, they will be refused + * anyway because they will mismatch on fake salt. + */ + +/* Dispatch handlers */ +static void input_userauth_jpake_client_step1(int, u_int32_t, void *); +static void input_userauth_jpake_client_step2(int, u_int32_t, void *); +static void input_userauth_jpake_client_confirm(int, u_int32_t, void *); + +static int auth2_jpake_start(Authctxt *); + +/* import */ +extern ServerOptions options; +extern u_char *session_id2; +extern u_int session_id2_len; + +/* + * Attempt J-PAKE authentication. + */ +static int +userauth_jpake(Authctxt *authctxt) +{ + int authenticated = 0; + + packet_check_eom(); + + debug("jpake-01@openssh.com requested"); + + if (authctxt->user != NULL) { + if (authctxt->jpake_ctx == NULL) + authctxt->jpake_ctx = jpake_new(); + if (options.zero_knowledge_password_authentication) + authenticated = auth2_jpake_start(authctxt); + } + + return authenticated; +} + +Authmethod method_jpake = { + "jpake-01@openssh.com", + userauth_jpake, + &options.zero_knowledge_password_authentication +}; + +/* Clear context and callbacks */ +void +auth2_jpake_stop(Authctxt *authctxt) +{ + /* unregister callbacks */ + dispatch_set(SSH2_MSG_USERAUTH_JPAKE_CLIENT_STEP1, NULL); + dispatch_set(SSH2_MSG_USERAUTH_JPAKE_CLIENT_STEP2, NULL); + dispatch_set(SSH2_MSG_USERAUTH_JPAKE_CLIENT_CONFIRM, NULL); + if (authctxt->jpake_ctx != NULL) { + jpake_free(authctxt->jpake_ctx); + authctxt->jpake_ctx = NULL; + } +} + +/* Returns 1 if 'c' is a valid crypt(3) salt character, 0 otherwise */ +static int +valid_crypt_salt(int c) +{ + if (c >= 'A' && c <= 'Z') + return 1; + if (c >= 'a' && c <= 'z') + return 1; + if (c >= '.' && c <= '9') + return 1; + return 0; +} + +/* + * Derive fake salt as H(username || first_private_host_key) + * This provides relatively stable fake salts for non-existent + * users and avoids the jpake method becoming an account validity + * oracle. + */ +static void +derive_rawsalt(const char *username, u_char *rawsalt, u_int len) +{ + u_char *digest; + u_int digest_len; + Buffer b; + Key *k; + + buffer_init(&b); + buffer_put_cstring(&b, username); + if ((k = get_hostkey_by_index(0)) == NULL || + (k->flags & KEY_FLAG_EXT)) + fatal("%s: no hostkeys", __func__); + switch (k->type) { + case KEY_RSA1: + case KEY_RSA: + if (k->rsa->p == NULL || k->rsa->q == NULL) + fatal("%s: RSA key missing p and/or q", __func__); + buffer_put_bignum2(&b, k->rsa->p); + buffer_put_bignum2(&b, k->rsa->q); + break; + case KEY_DSA: + if (k->dsa->priv_key == NULL) + fatal("%s: DSA key missing priv_key", __func__); + buffer_put_bignum2(&b, k->dsa->priv_key); + break; + default: + fatal("%s: unknown key type %d", __func__, k->type); + } + if (hash_buffer(buffer_ptr(&b), buffer_len(&b), EVP_sha256(), + &digest, &digest_len) != 0) + fatal("%s: hash_buffer", __func__); + buffer_free(&b); + if (len > digest_len) + fatal("%s: not enough bytes for rawsalt (want %u have %u)", + __func__, len, digest_len); + memcpy(rawsalt, digest, len); + bzero(digest, digest_len); + xfree(digest); +} + +/* ASCII an integer [0, 64) for inclusion in a password/salt */ +static char +pw_encode64(u_int i64) +{ + const u_char e64[] = + "./0123456789ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz"; + return e64[i64 % 64]; +} + +/* Generate ASCII salt bytes for user */ +static char * +makesalt(u_int want, const char *user) +{ + u_char rawsalt[32]; + static char ret[33]; + u_int i; + + if (want > sizeof(ret) - 1) + fatal("%s: want %u", __func__, want); + + derive_rawsalt(user, rawsalt, sizeof(rawsalt)); + bzero(ret, sizeof(ret)); + for (i = 0; i < want; i++) + ret[i] = pw_encode64(rawsalt[i]); + bzero(rawsalt, sizeof(rawsalt)); + + return ret; +} + +/* + * Select the system's default password hashing scheme and generate + * a stable fake salt under it for use by a non-existent account. + * Prevents jpake method being used to infer the validity of accounts. + */ +static void +fake_salt_and_scheme(Authctxt *authctxt, char **salt, char **scheme) +{ + char *rounds_s, *style; + long long rounds; + login_cap_t *lc; + + + if ((lc = login_getclass(authctxt->pw->pw_class)) == NULL && + (lc = login_getclass(NULL)) == NULL) + fatal("%s: login_getclass failed", __func__); + style = login_getcapstr(lc, "localcipher", NULL, NULL); + if (style == NULL) + style = xstrdup("blowfish,6"); + login_close(lc); + + if ((rounds_s = strchr(style, ',')) != NULL) + *rounds_s++ = '\0'; + rounds = strtonum(rounds_s, 1, 1<<31, NULL); + + if (strcmp(style, "md5") == 0) { + xasprintf(salt, "$1$%s$", makesalt(8, authctxt->user)); + *scheme = xstrdup("md5"); + } else if (strcmp(style, "old") == 0) { + *salt = xstrdup(makesalt(2, authctxt->user)); + *scheme = xstrdup("crypt"); + } else if (strcmp(style, "newsalt") == 0) { + rounds = MAX(rounds, 7250); + rounds = MIN(rounds, (1<<24) - 1); + xasprintf(salt, "_%c%c%c%c%s", + pw_encode64(rounds), pw_encode64(rounds >> 6), + pw_encode64(rounds >> 12), pw_encode64(rounds >> 18), + makesalt(4, authctxt->user)); + *scheme = xstrdup("crypt-extended"); + } else { + /* Default to blowfish */ + rounds = MAX(rounds, 3); + rounds = MIN(rounds, 31); + xasprintf(salt, "$2a$%02lld$%s", rounds, + makesalt(22, authctxt->user)); + *scheme = xstrdup("bcrypt"); + } + xfree(style); + debug3("%s: fake %s salt for user %s: %s", + __func__, *scheme, authctxt->user, *salt); +} + +/* + * Fetch password hashing scheme, password salt and derive shared secret + * for user. If user does not exist, a fake but stable and user-unique + * salt will be returned. + */ +void +auth2_jpake_get_pwdata(Authctxt *authctxt, BIGNUM **s, + char **hash_scheme, char **salt) +{ + char *cp; + u_char *secret; + u_int secret_len, salt_len; + +#ifdef JPAKE_DEBUG + debug3("%s: valid %d pw %.5s...", __func__, + authctxt->valid, authctxt->pw->pw_passwd); +#endif + + *salt = NULL; + *hash_scheme = NULL; + if (authctxt->valid) { + if (strncmp(authctxt->pw->pw_passwd, "$2$", 3) == 0 && + strlen(authctxt->pw->pw_passwd) > 28) { + /* + * old-variant bcrypt: + * "$2$", 2 digit rounds, "$", 22 bytes salt + */ + salt_len = 3 + 2 + 1 + 22 + 1; + *salt = xmalloc(salt_len); + strlcpy(*salt, authctxt->pw->pw_passwd, salt_len); + *hash_scheme = xstrdup("bcrypt"); + } else if (strncmp(authctxt->pw->pw_passwd, "$2a$", 4) == 0 && + strlen(authctxt->pw->pw_passwd) > 29) { + /* + * current-variant bcrypt: + * "$2a$", 2 digit rounds, "$", 22 bytes salt + */ + salt_len = 4 + 2 + 1 + 22 + 1; + *salt = xmalloc(salt_len); + strlcpy(*salt, authctxt->pw->pw_passwd, salt_len); + *hash_scheme = xstrdup("bcrypt"); + } else if (strncmp(authctxt->pw->pw_passwd, "$1$", 3) == 0 && + strlen(authctxt->pw->pw_passwd) > 5) { + /* + * md5crypt: + * "$1$", salt until "$" + */ + cp = strchr(authctxt->pw->pw_passwd + 3, '$'); + if (cp != NULL) { + salt_len = (cp - authctxt->pw->pw_passwd) + 1; + *salt = xmalloc(salt_len); + strlcpy(*salt, authctxt->pw->pw_passwd, + salt_len); + *hash_scheme = xstrdup("md5crypt"); + } + } else if (strncmp(authctxt->pw->pw_passwd, "_", 1) == 0 && + strlen(authctxt->pw->pw_passwd) > 9) { + /* + * BSDI extended crypt: + * "_", 4 digits count, 4 chars salt + */ + salt_len = 1 + 4 + 4 + 1; + *salt = xmalloc(salt_len); + strlcpy(*salt, authctxt->pw->pw_passwd, salt_len); + *hash_scheme = xstrdup("crypt-extended"); + } else if (strlen(authctxt->pw->pw_passwd) == 13 && + valid_crypt_salt(authctxt->pw->pw_passwd[0]) && + valid_crypt_salt(authctxt->pw->pw_passwd[1])) { + /* + * traditional crypt: + * 2 chars salt + */ + salt_len = 2 + 1; + *salt = xmalloc(salt_len); + strlcpy(*salt, authctxt->pw->pw_passwd, salt_len); + *hash_scheme = xstrdup("crypt"); + } + if (*salt == NULL) { + debug("%s: unrecognised crypt scheme for user %s", + __func__, authctxt->pw->pw_name); + } + } + if (*salt == NULL) + fake_salt_and_scheme(authctxt, salt, hash_scheme); + + if (hash_buffer(authctxt->pw->pw_passwd, + strlen(authctxt->pw->pw_passwd), EVP_sha256(), + &secret, &secret_len) != 0) + fatal("%s: hash_buffer", __func__); + if ((*s = BN_bin2bn(secret, secret_len, NULL)) == NULL) + fatal("%s: BN_bin2bn (secret)", __func__); +#ifdef JPAKE_DEBUG + debug3("%s: salt = %s (len %u)", __func__, + *salt, (u_int)strlen(*salt)); + debug3("%s: scheme = %s", __func__, *hash_scheme); + JPAKE_DEBUG_BN((*s, "%s: s = ", __func__)); +#endif + bzero(secret, secret_len); + xfree(secret); +} + +/* + * Being authentication attempt. + * Note, sets authctxt->postponed while in subprotocol + */ +static int +auth2_jpake_start(Authctxt *authctxt) +{ + struct jpake_ctx *pctx = authctxt->jpake_ctx; + u_char *x3_proof, *x4_proof; + u_int x3_proof_len, x4_proof_len; + char *salt, *hash_scheme; + + debug("%s: start", __func__); + + PRIVSEP(jpake_step1(pctx->grp, + &pctx->server_id, &pctx->server_id_len, + &pctx->x3, &pctx->x4, &pctx->g_x3, &pctx->g_x4, + &x3_proof, &x3_proof_len, + &x4_proof, &x4_proof_len)); + + PRIVSEP(auth2_jpake_get_pwdata(authctxt, &pctx->s, + &hash_scheme, &salt)); + + if (!use_privsep) + JPAKE_DEBUG_CTX((pctx, "step 1 sending in %s", __func__)); + + packet_start(SSH2_MSG_USERAUTH_JPAKE_SERVER_STEP1); + packet_put_cstring(hash_scheme); + packet_put_cstring(salt); + packet_put_string(pctx->server_id, pctx->server_id_len); + packet_put_bignum2(pctx->g_x3); + packet_put_bignum2(pctx->g_x4); + packet_put_string(x3_proof, x3_proof_len); + packet_put_string(x4_proof, x4_proof_len); + packet_send(); + packet_write_wait(); + + bzero(hash_scheme, strlen(hash_scheme)); + bzero(salt, strlen(salt)); + xfree(hash_scheme); + xfree(salt); + bzero(x3_proof, x3_proof_len); + bzero(x4_proof, x4_proof_len); + xfree(x3_proof); + xfree(x4_proof); + + /* Expect step 1 packet from peer */ + dispatch_set(SSH2_MSG_USERAUTH_JPAKE_CLIENT_STEP1, + input_userauth_jpake_client_step1); + + authctxt->postponed = 1; + return 0; +} + +/* ARGSUSED */ +static void +input_userauth_jpake_client_step1(int type, u_int32_t seq, void *ctxt) +{ + Authctxt *authctxt = ctxt; + struct jpake_ctx *pctx = authctxt->jpake_ctx; + u_char *x1_proof, *x2_proof, *x4_s_proof; + u_int x1_proof_len, x2_proof_len, x4_s_proof_len; + + /* Disable this message */ + dispatch_set(SSH2_MSG_USERAUTH_JPAKE_CLIENT_STEP1, NULL); + + /* Fetch step 1 values */ + if ((pctx->g_x1 = BN_new()) == NULL || + (pctx->g_x2 = BN_new()) == NULL) + fatal("%s: BN_new", __func__); + pctx->client_id = packet_get_string(&pctx->client_id_len); + packet_get_bignum2(pctx->g_x1); + packet_get_bignum2(pctx->g_x2); + x1_proof = packet_get_string(&x1_proof_len); + x2_proof = packet_get_string(&x2_proof_len); + packet_check_eom(); + + if (!use_privsep) + JPAKE_DEBUG_CTX((pctx, "step 1 received in %s", __func__)); + + PRIVSEP(jpake_step2(pctx->grp, pctx->s, pctx->g_x3, + pctx->g_x1, pctx->g_x2, pctx->x4, + pctx->client_id, pctx->client_id_len, + pctx->server_id, pctx->server_id_len, + x1_proof, x1_proof_len, + x2_proof, x2_proof_len, + &pctx->b, + &x4_s_proof, &x4_s_proof_len)); + + bzero(x1_proof, x1_proof_len); + bzero(x2_proof, x2_proof_len); + xfree(x1_proof); + xfree(x2_proof); + + if (!use_privsep) + JPAKE_DEBUG_CTX((pctx, "step 2 sending in %s", __func__)); + + /* Send values for step 2 */ + packet_start(SSH2_MSG_USERAUTH_JPAKE_SERVER_STEP2); + packet_put_bignum2(pctx->b); + packet_put_string(x4_s_proof, x4_s_proof_len); + packet_send(); + packet_write_wait(); + + bzero(x4_s_proof, x4_s_proof_len); + xfree(x4_s_proof); + + /* Expect step 2 packet from peer */ + dispatch_set(SSH2_MSG_USERAUTH_JPAKE_CLIENT_STEP2, + input_userauth_jpake_client_step2); +} + +/* ARGSUSED */ +static void +input_userauth_jpake_client_step2(int type, u_int32_t seq, void *ctxt) +{ + Authctxt *authctxt = ctxt; + struct jpake_ctx *pctx = authctxt->jpake_ctx; + u_char *x2_s_proof; + u_int x2_s_proof_len; + + /* Disable this message */ + dispatch_set(SSH2_MSG_USERAUTH_JPAKE_CLIENT_STEP2, NULL); + + if ((pctx->a = BN_new()) == NULL) + fatal("%s: BN_new", __func__); + + /* Fetch step 2 values */ + packet_get_bignum2(pctx->a); + x2_s_proof = packet_get_string(&x2_s_proof_len); + packet_check_eom(); + + if (!use_privsep) + JPAKE_DEBUG_CTX((pctx, "step 2 received in %s", __func__)); + + /* Derive shared key and calculate confirmation hash */ + PRIVSEP(jpake_key_confirm(pctx->grp, pctx->s, pctx->a, + pctx->x4, pctx->g_x3, pctx->g_x4, pctx->g_x1, pctx->g_x2, + pctx->server_id, pctx->server_id_len, + pctx->client_id, pctx->client_id_len, + session_id2, session_id2_len, + x2_s_proof, x2_s_proof_len, + &pctx->k, + &pctx->h_k_sid_sessid, &pctx->h_k_sid_sessid_len)); + + bzero(x2_s_proof, x2_s_proof_len); + xfree(x2_s_proof); + + if (!use_privsep) + JPAKE_DEBUG_CTX((pctx, "confirm sending in %s", __func__)); + + /* Send key confirmation proof */ + packet_start(SSH2_MSG_USERAUTH_JPAKE_SERVER_CONFIRM); + packet_put_string(pctx->h_k_sid_sessid, pctx->h_k_sid_sessid_len); + packet_send(); + packet_write_wait(); + + /* Expect confirmation from peer */ + dispatch_set(SSH2_MSG_USERAUTH_JPAKE_CLIENT_CONFIRM, + input_userauth_jpake_client_confirm); +} + +/* ARGSUSED */ +static void +input_userauth_jpake_client_confirm(int type, u_int32_t seq, void *ctxt) +{ + Authctxt *authctxt = ctxt; + struct jpake_ctx *pctx = authctxt->jpake_ctx; + int authenticated = 0; + + /* Disable this message */ + dispatch_set(SSH2_MSG_USERAUTH_JPAKE_CLIENT_CONFIRM, NULL); + + pctx->h_k_cid_sessid = packet_get_string(&pctx->h_k_cid_sessid_len); + packet_check_eom(); + + if (!use_privsep) + JPAKE_DEBUG_CTX((pctx, "confirm received in %s", __func__)); + + /* Verify expected confirmation hash */ + if (PRIVSEP(jpake_check_confirm(pctx->k, + pctx->client_id, pctx->client_id_len, + session_id2, session_id2_len, + pctx->h_k_cid_sessid, pctx->h_k_cid_sessid_len)) == 1) + authenticated = authctxt->valid ? 1 : 0; + else + debug("%s: confirmation mismatch", __func__); + + /* done */ + authctxt->postponed = 0; + jpake_free(authctxt->jpake_ctx); + authctxt->jpake_ctx = NULL; + userauth_finish(authctxt, authenticated, method_jpake.name); +} + +#endif /* JPAKE */ + @@ -1,4 +1,4 @@ -/* $OpenBSD: auth2.c,v 1.119 2008/07/04 23:30:16 djm Exp $ */ +/* $OpenBSD: auth2.c,v 1.120 2008/11/04 08:22:12 djm Exp $ */ /* * Copyright (c) 2000 Markus Friedl. All rights reserved. * @@ -71,6 +71,9 @@ extern Authmethod method_hostbased; #ifdef GSSAPI extern Authmethod method_gssapi; #endif +#ifdef JPAKE +extern Authmethod method_jpake; +#endif Authmethod *authmethods[] = { &method_none, @@ -78,6 +81,9 @@ Authmethod *authmethods[] = { #ifdef GSSAPI &method_gssapi, #endif +#ifdef JPAKE + &method_jpake, +#endif &method_passwd, &method_kbdint, &method_hostbased, @@ -257,8 +263,12 @@ input_userauth_request(int type, u_int32_t seq, void *ctxt) } /* reset state */ auth2_challenge_stop(authctxt); +#ifdef JPAKE + auth2_jpake_stop(authctxt); +#endif #ifdef GSSAPI + /* XXX move to auth2_gssapi_stop() */ dispatch_set(SSH2_MSG_USERAUTH_GSSAPI_TOKEN, NULL); dispatch_set(SSH2_MSG_USERAUTH_GSSAPI_EXCHANGE_COMPLETE, NULL); #endif diff --git a/jpake.c b/jpake.c new file mode 100644 index 00000000..565f2e25 --- /dev/null +++ b/jpake.c @@ -0,0 +1,604 @@ +/* $OpenBSD: jpake.c,v 1.1 2008/11/04 08:22:12 djm Exp $ */ +/* + * Copyright (c) 2008 Damien Miller. All rights reserved. + * + * Permission to use, copy, modify, and distribute this software for any + * purpose with or without fee is hereby granted, provided that the above + * copyright notice and this permission notice appear in all copies. + * + * THE SOFTWARE IS PROVIDED "AS IS" AND THE AUTHOR DISCLAIMS ALL WARRANTIES + * WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF + * MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR + * ANY SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES + * WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR PROFITS, WHETHER IN AN + * ACTION OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING OUT OF + * OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE. + */ + +/* + * Shared components of zero-knowledge password auth using J-PAKE protocol + * as described in: + * + * F. Hao, P. Ryan, "Password Authenticated Key Exchange by Juggling", + * 16th Workshop on Security Protocols, Cambridge, April 2008 + * + * http://grouper.ieee.org/groups/1363/Research/contributions/hao-ryan-2008.pdf + */ + +#include "includes.h" + +#include <sys/types.h> + +#include <stdio.h> +#include <string.h> +#include <stdarg.h> + +#include <openssl/bn.h> +#include <openssl/evp.h> + +#include "xmalloc.h" +#include "ssh2.h" +#include "key.h" +#include "hostfile.h" +#include "auth.h" +#include "buffer.h" +#include "packet.h" +#include "dispatch.h" +#include "log.h" + +#include "jpake.h" + +#ifdef JPAKE + +/* RFC3526 group 5, 1536 bits */ +#define JPAKE_GROUP_G "2" +#define JPAKE_GROUP_P \ + "FFFFFFFFFFFFFFFFC90FDAA22168C234C4C6628B80DC1CD129024E088A67CC74" \ + "020BBEA63B139B22514A08798E3404DDEF9519B3CD3A431B302B0A6DF25F1437" \ + "4FE1356D6D51C245E485B576625E7EC6F44C42E9A637ED6B0BFF5CB6F406B7ED" \ + "EE386BFB5A899FA5AE9F24117C4B1FE649286651ECE45B3DC2007CB8A163BF05" \ + "98DA48361C55D39A69163FA8FD24CF5F83655D23DCA3AD961C62F356208552BB" \ + "9ED529077096966D670C354E4ABC9804F1746C08CA237327FFFFFFFFFFFFFFFF" + +struct jpake_group * +jpake_default_group(void) +{ + struct jpake_group *ret; + + ret = xmalloc(sizeof(*ret)); + ret->p = ret->q = ret->g = NULL; + if (BN_hex2bn(&ret->p, JPAKE_GROUP_P) == 0 || + BN_hex2bn(&ret->g, JPAKE_GROUP_G) == 0) + fatal("%s: BN_hex2bn", __func__); + /* Subgroup order is p/2 (p is a safe prime) */ + if ((ret->q = BN_new()) == NULL) + fatal("%s: BN_new", __func__); + if (BN_rshift1(ret->q, ret->p) != 1) + fatal("%s: BN_rshift1", __func__); + + return ret; +} + +/* + * Generate uniformly distributed random number in range (1, high). + * Return number on success, NULL on failure. + */ +BIGNUM * +bn_rand_range_gt_one(const BIGNUM *high) +{ + BIGNUM *r, *tmp; + int success = -1; + + if ((tmp = BN_new()) == NULL) { + error("%s: BN_new", __func__); + return NULL; + } + if ((r = BN_new()) == NULL) { + error("%s: BN_new failed", __func__); + goto out; + } + if (BN_set_word(tmp, 2) != 1) { + error("%s: BN_set_word(tmp, 2)", __func__); + goto out; + } + if (BN_sub(tmp, high, tmp) == -1) { + error("%s: BN_sub failed (tmp = high - 2)", __func__); + goto out; + } + if (BN_rand_range(r, tmp) == -1) { + error("%s: BN_rand_range failed", __func__); + goto out; + } + if (BN_set_word(tmp, 2) != 1) { + error("%s: BN_set_word(tmp, 2)", __func__); + goto out; + } + if (BN_add(r, r, tmp) == -1) { + error("%s: BN_add failed (r = r + 2)", __func__); + goto out; + } + success = 0; + out: + BN_clear_free(tmp); + if (success == 0) + return r; + BN_clear_free(r); + return NULL; +} + +/* + * Hash contents of buffer 'b' with hash 'md'. Returns 0 on success, + * with digest via 'digestp' (caller to free) and length via 'lenp'. + * Returns -1 on failure. + */ +int +hash_buffer(const u_char *buf, u_int len, const EVP_MD *md, + u_char **digestp, u_int *lenp) +{ + u_char digest[EVP_MAX_MD_SIZE]; + u_int digest_len; + EVP_MD_CTX evp_md_ctx; + int success = -1; + + EVP_MD_CTX_init(&evp_md_ctx); + + if (EVP_DigestInit_ex(&evp_md_ctx, md, NULL) != 1) { + error("%s: EVP_DigestInit_ex", __func__); + goto out; + } + if (EVP_DigestUpdate(&evp_md_ctx, buf, len) != 1) { + error("%s: EVP_DigestUpdate", __func__); + goto out; + } + if (EVP_DigestFinal_ex(&evp_md_ctx, digest, &digest_len) != 1) { + error("%s: EVP_DigestFinal_ex", __func__); + goto out; + } + *digestp = xmalloc(digest_len); + *lenp = digest_len; + memcpy(*digestp, digest, *lenp); + success = 0; + out: + EVP_MD_CTX_cleanup(&evp_md_ctx); + bzero(digest, sizeof(digest)); + digest_len = 0; + return success; +} + +/* print formatted string followed by bignum */ +void +jpake_debug3_bn(const BIGNUM *n, const char *fmt, ...) +{ + char *out, *h; + va_list args; + + out = NULL; + va_start(args, fmt); + vasprintf(&out, fmt, args); + va_end(args); + if (out == NULL) + fatal("%s: vasprintf failed", __func__); + + if (n == NULL) + debug3("%s(null)", out); + else { + h = BN_bn2hex(n); + debug3("%s0x%s", out, h); + free(h); + } + free(out); +} + +/* print formatted string followed by buffer contents in hex */ +void +jpake_debug3_buf(const u_char *buf, u_int len, const char *fmt, ...) +{ + char *out, h[65]; + u_int i, j; + va_list args; + + out = NULL; + va_start(args, fmt); + vasprintf(&out, fmt, args); + va_end(args); + if (out == NULL) + fatal("%s: vasprintf failed", __func__); + + debug3("%s length %u%s", out, len, buf == NULL ? " (null)" : ""); + free(out); + if (buf == NULL) + return; + + *h = '\0'; + for (i = j = 0; i < len; i++) { + snprintf(h + j, sizeof(h) - j, "%02x", buf[i]); + j += 2; + if (j >= sizeof(h) - 1 || i == len - 1) { + debug3(" %s", h); + *h = '\0'; + j = 0; + } + } +} + +struct jpake_ctx * +jpake_new(void) +{ + struct jpake_ctx *ret; + + ret = xcalloc(1, sizeof(*ret)); + + ret->grp = jpake_default_group(); + + ret->s = ret->k = NULL; + ret->x1 = ret->x2 = ret->x3 = ret->x4 = NULL; + ret->g_x1 = ret->g_x2 = ret->g_x3 = ret->g_x4 = NULL; + ret->a = ret->b = NULL; + + ret->client_id = ret->server_id = NULL; + ret->h_k_cid_sessid = ret->h_k_sid_sessid = NULL; + + debug3("%s: alloc %p", __func__, ret); + + return ret; +} + + +void +jpake_free(struct jpake_ctx *pctx) +{ + debug3("%s: free %p", __func__, pctx); + +#define JPAKE_BN_CLEAR_FREE(v) \ + do { \ + if ((v) != NULL) { \ + BN_clear_free(v); \ + (v) = NULL; \ + } \ + } while (0) +#define JPAKE_BUF_CLEAR_FREE(v, l) \ + do { \ + if ((v) != NULL) { \ + bzero((v), (l)); \ + xfree(v); \ + (v) = NULL; \ + (l) = 0; \ + } \ + } while (0) + + JPAKE_BN_CLEAR_FREE(pctx->s); + JPAKE_BN_CLEAR_FREE(pctx->k); + JPAKE_BN_CLEAR_FREE(pctx->x1); + JPAKE_BN_CLEAR_FREE(pctx->x2); + JPAKE_BN_CLEAR_FREE(pctx->x3); + JPAKE_BN_CLEAR_FREE(pctx->x4); + JPAKE_BN_CLEAR_FREE(pctx->g_x1); + JPAKE_BN_CLEAR_FREE(pctx->g_x2); + JPAKE_BN_CLEAR_FREE(pctx->g_x3); + JPAKE_BN_CLEAR_FREE(pctx->g_x4); + JPAKE_BN_CLEAR_FREE(pctx->a); + JPAKE_BN_CLEAR_FREE(pctx->b); + + JPAKE_BUF_CLEAR_FREE(pctx->client_id, pctx->client_id_len); + JPAKE_BUF_CLEAR_FREE(pctx->server_id, pctx->server_id_len); + JPAKE_BUF_CLEAR_FREE(pctx->h_k_cid_sessid, pctx->h_k_cid_sessid_len); + JPAKE_BUF_CLEAR_FREE(pctx->h_k_sid_sessid, pctx->h_k_sid_sessid_len); + +#undef JPAKE_BN_CLEAR_FREE +#undef JPAKE_BUF_CLEAR_FREE + + bzero(pctx, sizeof(pctx)); + xfree(pctx); +} + +/* dump entire jpake_ctx. NB. includes private values! */ +void +jpake_dump(struct jpake_ctx *pctx, const char *fmt, ...) +{ + char *out; + va_list args; + + out = NULL; + va_start(args, fmt); + vasprintf(&out, fmt, args); + va_end(args); + if (out == NULL) + fatal("%s: vasprintf failed", __func__); + + debug3("%s: %s (ctx at %p)", __func__, out, pctx); + if (pctx == NULL) { + free(out); + return; + } + +#define JPAKE_DUMP_BN(a) do { \ + if ((a) != NULL) \ + JPAKE_DEBUG_BN(((a), "%s = ", #a)); \ + } while (0) +#define JPAKE_DUMP_BUF(a, b) do { \ + if ((a) != NULL) \ + JPAKE_DEBUG_BUF((a, b, "%s", #a)); \ + } while (0) + + JPAKE_DUMP_BN(pctx->s); + JPAKE_DUMP_BN(pctx->k); + JPAKE_DUMP_BN(pctx->x1); + JPAKE_DUMP_BN(pctx->x2); + JPAKE_DUMP_BN(pctx->x3); + JPAKE_DUMP_BN(pctx->x4); + JPAKE_DUMP_BN(pctx->g_x1); + JPAKE_DUMP_BN(pctx->g_x2); + JPAKE_DUMP_BN(pctx->g_x3); + JPAKE_DUMP_BN(pctx->g_x4); + JPAKE_DUMP_BN(pctx->a); + JPAKE_DUMP_BN(pctx->b); + + JPAKE_DUMP_BUF(pctx->client_id, pctx->client_id_len); + JPAKE_DUMP_BUF(pctx->server_id, pctx->server_id_len); + JPAKE_DUMP_BUF(pctx->h_k_cid_sessid, pctx->h_k_cid_sessid_len); + JPAKE_DUMP_BUF(pctx->h_k_sid_sessid, pctx->h_k_sid_sessid_len); + + debug3("%s: %s done", __func__, out); + free(out); +} + +/* Shared parts of step 1 exchange calculation */ +void +jpake_step1(struct jpake_group *grp, + u_char **id, u_int *id_len, + BIGNUM **priv1, BIGNUM **priv2, BIGNUM **g_priv1, BIGNUM **g_priv2, + u_char **priv1_proof, u_int *priv1_proof_len, + u_char **priv2_proof, u_int *priv2_proof_len) +{ + BN_CTX *bn_ctx; + + if ((bn_ctx = BN_CTX_new()) == NULL) + fatal("%s: BN_CTX_new", __func__); + + /* Random nonce to prevent replay */ + *id = xmalloc(KZP_ID_LEN); + *id_len = KZP_ID_LEN; + arc4random_buf(*id, *id_len); + + /* + * x1/x3 is a random element of Zq + * x2/x4 is a random element of Z*q + * We also exclude [1] from x1/x3 candidates and [0, 1] from + * x2/x4 candiates to avoid possible degeneracy (i.e. g^0, g^1). + */ + if ((*priv1 = bn_rand_range_gt_one(grp->q)) == NULL || + (*priv2 = bn_rand_range_gt_one(grp->q)) == NULL) + fatal("%s: bn_rand_range_gt_one", __func__); + + /* + * client: g_x1 = g^x1 mod p / server: g_x3 = g^x3 mod p + * client: g_x2 = g^x2 mod p / server: g_x4 = g^x4 mod p + */ + if ((*g_priv1 = BN_new()) == NULL || + (*g_priv2 = BN_new()) == NULL) + fatal("%s: BN_new", __func__); + if (BN_mod_exp(*g_priv1, grp->g, *priv1, grp->p, bn_ctx) == -1) + fatal("%s: BN_mod_exp", __func__); + if (BN_mod_exp(*g_priv2, grp->g, *priv2, grp->p, bn_ctx) == -1) + fatal("%s: BN_mod_exp", __func__); + + /* Generate proofs for holding x1/x3 and x2/x4 */ + if (schnorr_sign(grp->p, grp->q, grp->g, + *priv1, *g_priv1, *id, *id_len, + priv1_proof, priv1_proof_len) != 0) + fatal("%s: schnorr_sign", __func__); + if (schnorr_sign(grp->p, grp->q, grp->g, + *priv2, *g_priv2, *id, *id_len, + priv2_proof, priv2_proof_len) != 0) + fatal("%s: schnorr_sign", __func__); + + BN_CTX_free(bn_ctx); +} + +/* Shared parts of step 2 exchange calculation */ +void +jpake_step2(struct jpake_group *grp, BIGNUM *s, + BIGNUM *mypub1, BIGNUM *theirpub1, BIGNUM *theirpub2, BIGNUM *mypriv2, + const u_char *theirid, u_int theirid_len, + const u_char *myid, u_int myid_len, + const u_char *theirpub1_proof, u_int theirpub1_proof_len, + const u_char *theirpub2_proof, u_int theirpub2_proof_len, + BIGNUM **newpub, + u_char **newpub_exponent_proof, u_int *newpub_exponent_proof_len) +{ + BN_CTX *bn_ctx; + BIGNUM *tmp, *exponent; + + /* Validate peer's step 1 values */ + if (BN_cmp(theirpub1, BN_value_one()) <= 0) + fatal("%s: theirpub1 <= 1", __func__); + if (BN_cmp(theirpub2, BN_value_one()) <= 0) + fatal("%s: theirpub2 <= 1", __func__); + + if (schnorr_verify(grp->p, grp->q, grp->g, theirpub1, + theirid, theirid_len, theirpub1_proof, theirpub1_proof_len) != 1) + fatal("%s: schnorr_verify theirpub1 failed", __func__); + if (schnorr_verify(grp->p, grp->q, grp->g, theirpub2, + theirid, theirid_len, theirpub2_proof, theirpub2_proof_len) != 1) + fatal("%s: schnorr_verify theirpub2 failed", __func__); + + if ((bn_ctx = BN_CTX_new()) == NULL) + fatal("%s: BN_CTX_new", __func__); + + if ((*newpub = BN_new()) == NULL || + (tmp = BN_new()) == NULL || + (exponent = BN_new()) == NULL) + fatal("%s: BN_new", __func__); + + /* + * client: exponent = x2 * s mod p + * server: exponent = x4 * s mod p + */ + if (BN_mod_mul(exponent, mypriv2, s, grp->q, bn_ctx) != 1) + fatal("%s: BN_mod_mul (exponent = mypriv2 * s mod p)", + __func__); + + /* + * client: tmp = g^(x1 + x3 + x4) mod p + * server: tmp = g^(x1 + x2 + x3) mod p + */ + if (BN_mod_mul(tmp, mypub1, theirpub1, grp->p, bn_ctx) != 1) + fatal("%s: BN_mod_mul (tmp = mypub1 * theirpub1 mod p)", + __func__); + if (BN_mod_mul(tmp, tmp, theirpub2, grp->p, bn_ctx) != 1) + fatal("%s: BN_mod_mul (tmp = tmp * theirpub2 mod p)", __func__); + + /* + * client: a = tmp^exponent = g^((x1+x3+x4) * x2 * s) mod p + * server: b = tmp^exponent = g^((x1+x2+x3) * x4 * s) mod p + */ + if (BN_mod_exp(*newpub, tmp, exponent, grp->p, bn_ctx) != 1) + fatal("%s: BN_mod_mul (newpub = tmp^exponent mod p)", __func__); + + JPAKE_DEBUG_BN((tmp, "%s: tmp = ", __func__)); + JPAKE_DEBUG_BN((exponent, "%s: exponent = ", __func__)); + + /* Note the generator here is 'tmp', not g */ + if (schnorr_sign(grp->p, grp->q, tmp, exponent, *newpub, + myid, myid_len, + newpub_exponent_proof, newpub_exponent_proof_len) != 0) + fatal("%s: schnorr_sign newpub", __func__); + + BN_clear_free(tmp); /* XXX stash for later use? */ + BN_clear_free(exponent); /* XXX stash for later use? (yes, in conf) */ + + BN_CTX_free(bn_ctx); +} + +/* Confirmation hash calculation */ +void +jpake_confirm_hash(const BIGNUM *k, + const u_char *endpoint_id, u_int endpoint_id_len, + const u_char *sess_id, u_int sess_id_len, + u_char **confirm_hash, u_int *confirm_hash_len) +{ + Buffer b; + + /* + * Calculate confirmation proof: + * client: H(k || client_id || session_id) + * server: H(k || server_id || session_id) + */ + buffer_init(&b); + buffer_put_bignum2(&b, k); + buffer_put_string(&b, endpoint_id, endpoint_id_len); + buffer_put_string(&b, sess_id, sess_id_len); + if (hash_buffer(buffer_ptr(&b), buffer_len(&b), EVP_sha256(), + confirm_hash, confirm_hash_len) != 0) + fatal("%s: hash_buffer", __func__); + buffer_free(&b); +} + +/* Shared parts of key derivation and confirmation calculation */ +void +jpake_key_confirm(struct jpake_group *grp, BIGNUM *s, BIGNUM *step2_val, + BIGNUM *mypriv2, BIGNUM *mypub1, BIGNUM *mypub2, + BIGNUM *theirpub1, BIGNUM *theirpub2, + const u_char *my_id, u_int my_id_len, + const u_char *their_id, u_int their_id_len, + const u_char *sess_id, u_int sess_id_len, + const u_char *theirpriv2_s_proof, u_int theirpriv2_s_proof_len, + BIGNUM **k, + u_char **confirm_hash, u_int *confirm_hash_len) +{ + BN_CTX *bn_ctx; + BIGNUM *tmp; + + if ((bn_ctx = BN_CTX_new()) == NULL) + fatal("%s: BN_CTX_new", __func__); + if ((tmp = BN_new()) == NULL || + (*k = BN_new()) == NULL) + fatal("%s: BN_new", __func__); + + /* Validate step 2 values */ + if (BN_cmp(step2_val, BN_value_one()) <= 0) + fatal("%s: step2_val <= 1", __func__); + + /* + * theirpriv2_s_proof is calculated with a different generator: + * tmp = g^(mypriv1+mypriv2+theirpub1) = g^mypub1*g^mypub2*g^theirpub1 + * Calculate it here so we can check the signature. + */ + if (BN_mod_mul(tmp, mypub1, mypub2, grp->p, bn_ctx) != 1) + fatal("%s: BN_mod_mul (tmp = mypub1 * mypub2 mod p)", __func__); + if (BN_mod_mul(tmp, tmp, theirpub1, grp->p, bn_ctx) != 1) + fatal("%s: BN_mod_mul (tmp = tmp * theirpub1 mod p)", __func__); + + JPAKE_DEBUG_BN((tmp, "%s: tmp = ", __func__)); + + if (schnorr_verify(grp->p, grp->q, tmp, step2_val, + their_id, their_id_len, + theirpriv2_s_proof, theirpriv2_s_proof_len) != 1) + fatal("%s: schnorr_verify theirpriv2_s_proof failed", __func__); + + /* + * Derive shared key: + * client: k = (b / g^(x2*x4*s))^x2 = g^((x1+x3)*x2*x4*s) + * server: k = (a / g^(x2*x4*s))^x4 = g^((x1+x3)*x2*x4*s) + * + * Computed as: + * client: k = (g_x4^(q - (x2 * s)) * b)^x2 mod p + * server: k = (g_x2^(q - (x4 * s)) * b)^x4 mod p + */ + if (BN_mul(tmp, mypriv2, s, bn_ctx) != 1) + fatal("%s: BN_mul (tmp = mypriv2 * s)", __func__); + if (BN_mod_sub(tmp, grp->q, tmp, grp->q, bn_ctx) != 1) + fatal("%s: BN_mod_sub (tmp = q - tmp mod q)", __func__); + if (BN_mod_exp(tmp, theirpub2, tmp, grp->p, bn_ctx) != 1) + fatal("%s: BN_mod_exp (tmp = theirpub2^tmp) mod p", __func__); + if (BN_mod_mul(tmp, tmp, step2_val, grp->p, bn_ctx) != 1) + fatal("%s: BN_mod_mul (tmp = tmp * step2_val) mod p", __func__); + if (BN_mod_exp(*k, tmp, mypriv2, grp->p, bn_ctx) != 1) + fatal("%s: BN_mod_exp (k = tmp^mypriv2) mod p", __func__); + + BN_CTX_free(bn_ctx); + BN_clear_free(tmp); + + jpake_confirm_hash(*k, my_id, my_id_len, sess_id, sess_id_len, + confirm_hash, confirm_hash_len); +} + +/* + * Calculate and check confirmation hash from peer. Returns 1 on success + * 0 on failure/mismatch. + */ +int +jpake_check_confirm(const BIGNUM *k, + const u_char *peer_id, u_int peer_id_len, + const u_char *sess_id, u_int sess_id_len, + const u_char *peer_confirm_hash, u_int peer_confirm_hash_len) +{ + u_char *expected_confirm_hash; + u_int expected_confirm_hash_len; + int success = 0; + + /* Calculate and verify expected confirmation hash */ + jpake_confirm_hash(k, peer_id, peer_id_len, sess_id, sess_id_len, + &expected_confirm_hash, &expected_confirm_hash_len); + + JPAKE_DEBUG_BUF((expected_confirm_hash, expected_confirm_hash_len, + "%s: expected confirm hash", __func__)); + JPAKE_DEBUG_BUF((peer_confirm_hash, peer_confirm_hash_len, + "%s: received confirm hash", __func__)); + + if (peer_confirm_hash_len != expected_confirm_hash_len) + error("%s: confirmation length mismatch (my %u them %u)", + __func__, expected_confirm_hash_len, peer_confirm_hash_len); + else if (memcmp(peer_confirm_hash, expected_confirm_hash, + expected_confirm_hash_len) == 0) + success = 1; + bzero(expected_confirm_hash, expected_confirm_hash_len); + xfree(expected_confirm_hash); + debug3("%s: success = %d", __func__, success); + return success; +} + +/* XXX main() function with tests */ + +#endif /* JPAKE */ + diff --git a/jpake.h b/jpake.h new file mode 100644 index 00000000..a3d800cd --- /dev/null +++ b/jpake.h @@ -0,0 +1,134 @@ +/* $OpenBSD: jpake.h,v 1.1 2008/11/04 08:22:13 djm Exp $ */ +/* + * Copyright (c) 2008 Damien Miller. All rights reserved. + * + * Permission to use, copy, modify, and distribute this software for any + * purpose with or without fee is hereby granted, provided that the above + * copyright notice and this permission notice appear in all copies. + * + * THE SOFTWARE IS PROVIDED "AS IS" AND THE AUTHOR DISCLAIMS ALL WARRANTIES + * WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF + * MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR + * ANY SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES + * WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR PROFITS, WHETHER IN AN + * ACTION OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING OUT OF + * OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE. + */ + +#ifndef JPAKE_H +#define JPAKE_H + +#include <sys/types.h> + +#include <openssl/bn.h> + +/* Set JPAKE_DEBUG in CFLAGS for privacy-violating debugging */ +#ifndef JPAKE_DEBUG +# define JPAKE_DEBUG_BN(a) +# define JPAKE_DEBUG_BUF(a) +# define JPAKE_DEBUG_CTX(a) +#else +# define JPAKE_DEBUG_BN(a) jpake_debug3_bn a +# define JPAKE_DEBUG_BUF(a) jpake_debug3_buf a +# define JPAKE_DEBUG_CTX(a) jpake_dump a +#endif /* SCHNORR_DEBUG */ + +struct jpake_group { + BIGNUM *p, *q, *g; +}; + +#define KZP_ID_LEN 16 /* Length of client and server IDs */ + +struct jpake_ctx { + /* Parameters */ + struct jpake_group *grp; + + /* Private values shared by client and server */ + BIGNUM *s; /* Secret (salted, crypted password) */ + BIGNUM *k; /* Derived key */ + + /* Client private values (NULL for server) */ + BIGNUM *x1; /* random in Zq */ + BIGNUM *x2; /* random in Z*q */ + + /* Server private values (NULL for server) */ + BIGNUM *x3; /* random in Zq */ + BIGNUM *x4; /* random in Z*q */ + + /* Step 1: C->S */ + u_char *client_id; /* Anti-replay nonce */ + u_int client_id_len; + BIGNUM *g_x1; /* g^x1 */ + BIGNUM *g_x2; /* g^x2 */ + + /* Step 1: S->C */ + u_char *server_id; /* Anti-replay nonce */ + u_int server_id_len; + BIGNUM *g_x3; /* g^x3 */ + BIGNUM *g_x4; /* g^x4 */ + + /* Step 2: C->S */ + BIGNUM *a; /* g^((x1+x3+x4)*x2*s) */ + + /* Step 2: S->C */ + BIGNUM *b; /* g^((x1+x2+x3)*x4*s) */ + + /* Confirmation: C->S */ + u_char *h_k_cid_sessid; /* H(k || client_id || session_id) */ + u_int h_k_cid_sessid_len; + + /* Confirmation: S->C */ + u_char *h_k_sid_sessid; /* H(k || server_id || session_id) */ + u_int h_k_sid_sessid_len; +}; + +/* jpake.c */ +struct jpake_group *jpake_default_group(void); +BIGNUM *bn_rand_range_gt_one(const BIGNUM *high); +int hash_buffer(const u_char *, u_int, const EVP_MD *, u_char **, u_int *); +void jpake_debug3_bn(const BIGNUM *, const char *, ...) + __attribute__((__nonnull__ (2))) + __attribute__((format(printf, 2, 3))); +void jpake_debug3_buf(const u_char *, u_int, const char *, ...) + __attribute__((__nonnull__ (3))) + __attribute__((format(printf, 3, 4))); +void jpake_dump(struct jpake_ctx *, const char *, ...) + __attribute__((__nonnull__ (2))) + __attribute__((format(printf, 2, 3))); +struct jpake_ctx *jpake_new(void); +void jpake_free(struct jpake_ctx *); + +void jpake_step1(struct jpake_group *, u_char **, u_int *, + BIGNUM **, BIGNUM **, BIGNUM **, BIGNUM **, + u_char **, u_int *, u_char **, u_int *); + +void jpake_step2(struct jpake_group *, BIGNUM *, + BIGNUM *, BIGNUM *, BIGNUM *, BIGNUM *, + const u_char *, u_int, const u_char *, u_int, + const u_char *, u_int, const u_char *, u_int, + BIGNUM **, u_char **, u_int *); + +void jpake_confirm_hash(const BIGNUM *, + const u_char *, u_int, + const u_char *, u_int, + u_char **, u_int *); + +void jpake_key_confirm(struct jpake_group *, BIGNUM *, BIGNUM *, + BIGNUM *, BIGNUM *, BIGNUM *, BIGNUM *, BIGNUM *, + const u_char *, u_int, const u_char *, u_int, + const u_char *, u_int, const u_char *, u_int, + BIGNUM **, u_char **, u_int *); + +int jpake_check_confirm(const BIGNUM *, const u_char *, u_int, + const u_char *, u_int, const u_char *, u_int); + +/* schnorr.c */ +int schnorr_sign(const BIGNUM *, const BIGNUM *, const BIGNUM *, + const BIGNUM *, const BIGNUM *, const u_char *, u_int , + u_char **, u_int *); +int schnorr_verify(const BIGNUM *, const BIGNUM *, const BIGNUM *, + const BIGNUM *, const u_char *, u_int, + const u_char *, u_int); + +#endif /* JPAKE_H */ + @@ -1,4 +1,4 @@ -/* $OpenBSD: monitor.c,v 1.99 2008/07/10 18:08:11 markus Exp $ */ +/* $OpenBSD: monitor.c,v 1.100 2008/11/04 08:22:13 djm Exp $ */ /* * Copyright 2002 Niels Provos <provos@citi.umich.edu> * Copyright 2002 Markus Friedl <markus@openbsd.org> @@ -87,6 +87,7 @@ #include "misc.h" #include "compat.h" #include "ssh2.h" +#include "jpake.h" #ifdef GSSAPI static Gssctxt *gsscontext = NULL; @@ -149,6 +150,11 @@ int mm_answer_rsa_challenge(int, Buffer *); int mm_answer_rsa_response(int, Buffer *); int mm_answer_sesskey(int, Buffer *); int mm_answer_sessid(int, Buffer *); +int mm_answer_jpake_get_pwdata(int, Buffer *); +int mm_answer_jpake_step1(int, Buffer *); +int mm_answer_jpake_step2(int, Buffer *); +int mm_answer_jpake_key_confirm(int, Buffer *); +int mm_answer_jpake_check_confirm(int, Buffer *); #ifdef USE_PAM int mm_answer_pam_start(int, Buffer *); @@ -234,6 +240,13 @@ struct mon_table mon_dispatch_proto20[] = { {MONITOR_REQ_GSSUSEROK, MON_AUTH, mm_answer_gss_userok}, {MONITOR_REQ_GSSCHECKMIC, MON_ISAUTH, mm_answer_gss_checkmic}, #endif +#ifdef JPAKE + {MONITOR_REQ_JPAKE_GET_PWDATA, MON_ONCE, mm_answer_jpake_get_pwdata}, + {MONITOR_REQ_JPAKE_STEP1, MON_ISAUTH, mm_answer_jpake_step1}, + {MONITOR_REQ_JPAKE_STEP2, MON_ONCE, mm_answer_jpake_step2}, + {MONITOR_REQ_JPAKE_KEY_CONFIRM, MON_ONCE, mm_answer_jpake_key_confirm}, + {MONITOR_REQ_JPAKE_CHECK_CONFIRM, MON_AUTH, mm_answer_jpake_check_confirm}, +#endif {0, 0, NULL} }; @@ -379,6 +392,15 @@ monitor_child_preauth(Authctxt *_authctxt, struct monitor *pmonitor) if (!authenticated) authctxt->failures++; } +#ifdef JPAKE + /* Cleanup JPAKE context after authentication */ + if (ent->flags & MON_AUTHDECIDE) { + if (authctxt->jpake_ctx != NULL) { + jpake_free(authctxt->jpake_ctx); + authctxt->jpake_ctx = NULL; + } + } +#endif } if (!authctxt->valid) @@ -1969,3 +1991,206 @@ mm_answer_gss_userok(int sock, Buffer *m) return (authenticated); } #endif /* GSSAPI */ + +#ifdef JPAKE +int +mm_answer_jpake_step1(int sock, Buffer *m) +{ + struct jpake_ctx *pctx; + u_char *x3_proof, *x4_proof; + u_int x3_proof_len, x4_proof_len; + + if (!options.zero_knowledge_password_authentication) + fatal("zero_knowledge_password_authentication disabled"); + + if (authctxt->jpake_ctx != NULL) + fatal("%s: authctxt->jpake_ctx already set (%p)", + __func__, authctxt->jpake_ctx); + authctxt->jpake_ctx = pctx = jpake_new(); + + jpake_step1(pctx->grp, + &pctx->server_id, &pctx->server_id_len, + &pctx->x3, &pctx->x4, &pctx->g_x3, &pctx->g_x4, + &x3_proof, &x3_proof_len, + &x4_proof, &x4_proof_len); + + JPAKE_DEBUG_CTX((pctx, "step1 done in %s", __func__)); + + buffer_clear(m); + + buffer_put_string(m, pctx->server_id, pctx->server_id_len); + buffer_put_bignum2(m, pctx->g_x3); + buffer_put_bignum2(m, pctx->g_x4); + buffer_put_string(m, x3_proof, x3_proof_len); + buffer_put_string(m, x4_proof, x4_proof_len); + + debug3("%s: sending step1", __func__); + mm_request_send(sock, MONITOR_ANS_JPAKE_STEP1, m); + + bzero(x3_proof, x3_proof_len); + bzero(x4_proof, x4_proof_len); + xfree(x3_proof); + xfree(x4_proof); + + monitor_permit(mon_dispatch, MONITOR_REQ_JPAKE_GET_PWDATA, 1); + monitor_permit(mon_dispatch, MONITOR_REQ_JPAKE_STEP1, 0); + + return 0; +} + +int +mm_answer_jpake_get_pwdata(int sock, Buffer *m) +{ + struct jpake_ctx *pctx = authctxt->jpake_ctx; + char *hash_scheme, *salt; + + if (pctx == NULL) + fatal("%s: pctx == NULL", __func__); + + auth2_jpake_get_pwdata(authctxt, &pctx->s, &hash_scheme, &salt); + + buffer_clear(m); + /* pctx->s is sensitive, not returned to slave */ + buffer_put_cstring(m, hash_scheme); + buffer_put_cstring(m, salt); + + debug3("%s: sending pwdata", __func__); + mm_request_send(sock, MONITOR_ANS_JPAKE_GET_PWDATA, m); + + bzero(hash_scheme, strlen(hash_scheme)); + bzero(salt, strlen(salt)); + xfree(hash_scheme); + xfree(salt); + + monitor_permit(mon_dispatch, MONITOR_REQ_JPAKE_STEP2, 1); + + return 0; +} + +int +mm_answer_jpake_step2(int sock, Buffer *m) +{ + struct jpake_ctx *pctx = authctxt->jpake_ctx; + u_char *x1_proof, *x2_proof, *x4_s_proof; + u_int x1_proof_len, x2_proof_len, x4_s_proof_len; + + if (pctx == NULL) + fatal("%s: pctx == NULL", __func__); + + if ((pctx->g_x1 = BN_new()) == NULL || + (pctx->g_x2 = BN_new()) == NULL) + fatal("%s: BN_new", __func__); + buffer_get_bignum2(m, pctx->g_x1); + buffer_get_bignum2(m, pctx->g_x2); + pctx->client_id = buffer_get_string(m, &pctx->client_id_len); + x1_proof = buffer_get_string(m, &x1_proof_len); + x2_proof = buffer_get_string(m, &x2_proof_len); + + jpake_step2(pctx->grp, pctx->s, pctx->g_x3, + pctx->g_x1, pctx->g_x2, pctx->x4, + pctx->client_id, pctx->client_id_len, + pctx->server_id, pctx->server_id_len, + x1_proof, x1_proof_len, + x2_proof, x2_proof_len, + &pctx->b, + &x4_s_proof, &x4_s_proof_len); + + JPAKE_DEBUG_CTX((pctx, "step2 done in %s", __func__)); + + bzero(x1_proof, x1_proof_len); + bzero(x2_proof, x2_proof_len); + xfree(x1_proof); + xfree(x2_proof); + + buffer_clear(m); + + buffer_put_bignum2(m, pctx->b); + buffer_put_string(m, x4_s_proof, x4_s_proof_len); + + debug3("%s: sending step2", __func__); + mm_request_send(sock, MONITOR_ANS_JPAKE_STEP2, m); + + bzero(x4_s_proof, x4_s_proof_len); + xfree(x4_s_proof); + + monitor_permit(mon_dispatch, MONITOR_REQ_JPAKE_KEY_CONFIRM, 1); + + return 0; +} + +int +mm_answer_jpake_key_confirm(int sock, Buffer *m) +{ + struct jpake_ctx *pctx = authctxt->jpake_ctx; + u_char *x2_s_proof; + u_int x2_s_proof_len; + + if (pctx == NULL) + fatal("%s: pctx == NULL", __func__); + + if ((pctx->a = BN_new()) == NULL) + fatal("%s: BN_new", __func__); + buffer_get_bignum2(m, pctx->a); + x2_s_proof = buffer_get_string(m, &x2_s_proof_len); + + jpake_key_confirm(pctx->grp, pctx->s, pctx->a, + pctx->x4, pctx->g_x3, pctx->g_x4, pctx->g_x1, pctx->g_x2, + pctx->server_id, pctx->server_id_len, + pctx->client_id, pctx->client_id_len, + session_id2, session_id2_len, + x2_s_proof, x2_s_proof_len, + &pctx->k, + &pctx->h_k_sid_sessid, &pctx->h_k_sid_sessid_len); + + JPAKE_DEBUG_CTX((pctx, "key_confirm done in %s", __func__)); + + bzero(x2_s_proof, x2_s_proof_len); + buffer_clear(m); + + /* pctx->k is sensitive, not sent */ + buffer_put_string(m, pctx->h_k_sid_sessid, pctx->h_k_sid_sessid_len); + + debug3("%s: sending confirmation hash", __func__); + mm_request_send(sock, MONITOR_ANS_JPAKE_KEY_CONFIRM, m); + + monitor_permit(mon_dispatch, MONITOR_REQ_JPAKE_CHECK_CONFIRM, 1); + + return 0; +} + +int +mm_answer_jpake_check_confirm(int sock, Buffer *m) +{ + int authenticated = 0; + u_char *peer_confirm_hash; + u_int peer_confirm_hash_len; + struct jpake_ctx *pctx = authctxt->jpake_ctx; + + if (pctx == NULL) + fatal("%s: pctx == NULL", __func__); + + peer_confirm_hash = buffer_get_string(m, &peer_confirm_hash_len); + + authenticated = jpake_check_confirm(pctx->k, + pctx->client_id, pctx->client_id_len, + session_id2, session_id2_len, + peer_confirm_hash, peer_confirm_hash_len) && authctxt->valid; + + JPAKE_DEBUG_CTX((pctx, "check_confirm done in %s", __func__)); + + bzero(peer_confirm_hash, peer_confirm_hash_len); + xfree(peer_confirm_hash); + + buffer_clear(m); + buffer_put_int(m, authenticated); + + debug3("%s: sending result %d", __func__, authenticated); + mm_request_send(sock, MONITOR_ANS_JPAKE_CHECK_CONFIRM, m); + + monitor_permit(mon_dispatch, MONITOR_REQ_JPAKE_STEP1, 1); + + auth_method = "jpake-01@openssh.com"; + return authenticated; +} + +#endif /* JPAKE */ @@ -1,4 +1,4 @@ -/* $OpenBSD: monitor.h,v 1.14 2006/03/25 22:22:43 djm Exp $ */ +/* $OpenBSD: monitor.h,v 1.15 2008/11/04 08:22:13 djm Exp $ */ /* * Copyright 2002 Niels Provos <provos@citi.umich.edu> @@ -60,7 +60,12 @@ enum monitor_reqtype { MONITOR_REQ_PAM_RESPOND, MONITOR_ANS_PAM_RESPOND, MONITOR_REQ_PAM_FREE_CTX, MONITOR_ANS_PAM_FREE_CTX, MONITOR_REQ_AUDIT_EVENT, MONITOR_REQ_AUDIT_COMMAND, - MONITOR_REQ_TERM + MONITOR_REQ_TERM, + MONITOR_REQ_JPAKE_STEP1, MONITOR_ANS_JPAKE_STEP1, + MONITOR_REQ_JPAKE_GET_PWDATA, MONITOR_ANS_JPAKE_GET_PWDATA, + MONITOR_REQ_JPAKE_STEP2, MONITOR_ANS_JPAKE_STEP2, + MONITOR_REQ_JPAKE_KEY_CONFIRM, MONITOR_ANS_JPAKE_KEY_CONFIRM, + MONITOR_REQ_JPAKE_CHECK_CONFIRM, MONITOR_ANS_JPAKE_CHECK_CONFIRM, }; struct mm_master; diff --git a/monitor_wrap.c b/monitor_wrap.c index 40463d07..0986fc51 100644 --- a/monitor_wrap.c +++ b/monitor_wrap.c @@ -1,4 +1,4 @@ -/* $OpenBSD: monitor_wrap.c,v 1.63 2008/07/10 18:08:11 markus Exp $ */ +/* $OpenBSD: monitor_wrap.c,v 1.64 2008/11/04 08:22:13 djm Exp $ */ /* * Copyright 2002 Niels Provos <provos@citi.umich.edu> * Copyright 2002 Markus Friedl <markus@openbsd.org> @@ -40,6 +40,7 @@ #include <openssl/bn.h> #include <openssl/dh.h> +#include <openssl/evp.h> #include "openbsd-compat/sys-queue.h" #include "xmalloc.h" @@ -70,7 +71,7 @@ #include "atomicio.h" #include "monitor_fdpass.h" #include "misc.h" -#include "servconf.h" +#include "jpake.h" #include "channels.h" #include "session.h" @@ -1256,3 +1257,165 @@ mm_ssh_gssapi_userok(char *user) return (authenticated); } #endif /* GSSAPI */ + +#ifdef JPAKE +void +mm_auth2_jpake_get_pwdata(Authctxt *authctxt, BIGNUM **s, + char **hash_scheme, char **salt) +{ + Buffer m; + + debug3("%s entering", __func__); + + buffer_init(&m); + mm_request_send(pmonitor->m_recvfd, + MONITOR_REQ_JPAKE_GET_PWDATA, &m); + + debug3("%s: waiting for MONITOR_ANS_JPAKE_GET_PWDATA", __func__); + mm_request_receive_expect(pmonitor->m_recvfd, + MONITOR_ANS_JPAKE_GET_PWDATA, &m); + + *hash_scheme = buffer_get_string(&m, NULL); + *salt = buffer_get_string(&m, NULL); + + buffer_free(&m); +} + +void +mm_jpake_step1(struct jpake_group *grp, + u_char **id, u_int *id_len, + BIGNUM **priv1, BIGNUM **priv2, BIGNUM **g_priv1, BIGNUM **g_priv2, + u_char **priv1_proof, u_int *priv1_proof_len, + u_char **priv2_proof, u_int *priv2_proof_len) +{ + Buffer m; + + debug3("%s entering", __func__); + + buffer_init(&m); + mm_request_send(pmonitor->m_recvfd, + MONITOR_REQ_JPAKE_STEP1, &m); + + debug3("%s: waiting for MONITOR_ANS_JPAKE_STEP1", __func__); + mm_request_receive_expect(pmonitor->m_recvfd, + MONITOR_ANS_JPAKE_STEP1, &m); + + if ((*priv1 = BN_new()) == NULL || + (*priv2 = BN_new()) == NULL || + (*g_priv1 = BN_new()) == NULL || + (*g_priv2 = BN_new()) == NULL) + fatal("%s: BN_new", __func__); + + *id = buffer_get_string(&m, id_len); + /* priv1 and priv2 are, well, private */ + buffer_get_bignum2(&m, *g_priv1); + buffer_get_bignum2(&m, *g_priv2); + *priv1_proof = buffer_get_string(&m, priv1_proof_len); + *priv2_proof = buffer_get_string(&m, priv2_proof_len); + + buffer_free(&m); +} + +void +mm_jpake_step2(struct jpake_group *grp, BIGNUM *s, + BIGNUM *mypub1, BIGNUM *theirpub1, BIGNUM *theirpub2, BIGNUM *mypriv2, + const u_char *theirid, u_int theirid_len, + const u_char *myid, u_int myid_len, + const u_char *theirpub1_proof, u_int theirpub1_proof_len, + const u_char *theirpub2_proof, u_int theirpub2_proof_len, + BIGNUM **newpub, + u_char **newpub_exponent_proof, u_int *newpub_exponent_proof_len) +{ + Buffer m; + + debug3("%s entering", __func__); + + buffer_init(&m); + /* monitor already has all bignums except theirpub1, theirpub2 */ + buffer_put_bignum2(&m, theirpub1); + buffer_put_bignum2(&m, theirpub2); + /* monitor already knows our id */ + buffer_put_string(&m, theirid, theirid_len); + buffer_put_string(&m, theirpub1_proof, theirpub1_proof_len); + buffer_put_string(&m, theirpub2_proof, theirpub2_proof_len); + + mm_request_send(pmonitor->m_recvfd, + MONITOR_REQ_JPAKE_STEP2, &m); + + debug3("%s: waiting for MONITOR_ANS_JPAKE_STEP2", __func__); + mm_request_receive_expect(pmonitor->m_recvfd, + MONITOR_ANS_JPAKE_STEP2, &m); + + if ((*newpub = BN_new()) == NULL) + fatal("%s: BN_new", __func__); + + buffer_get_bignum2(&m, *newpub); + *newpub_exponent_proof = buffer_get_string(&m, + newpub_exponent_proof_len); + + buffer_free(&m); +} + +void +mm_jpake_key_confirm(struct jpake_group *grp, BIGNUM *s, BIGNUM *step2_val, + BIGNUM *mypriv2, BIGNUM *mypub1, BIGNUM *mypub2, + BIGNUM *theirpub1, BIGNUM *theirpub2, + const u_char *my_id, u_int my_id_len, + const u_char *their_id, u_int their_id_len, + const u_char *sess_id, u_int sess_id_len, + const u_char *theirpriv2_s_proof, u_int theirpriv2_s_proof_len, + BIGNUM **k, + u_char **confirm_hash, u_int *confirm_hash_len) +{ + Buffer m; + + debug3("%s entering", __func__); + + buffer_init(&m); + /* monitor already has all bignums except step2_val */ + buffer_put_bignum2(&m, step2_val); + /* monitor already knows all the ids */ + buffer_put_string(&m, theirpriv2_s_proof, theirpriv2_s_proof_len); + + mm_request_send(pmonitor->m_recvfd, + MONITOR_REQ_JPAKE_KEY_CONFIRM, &m); + + debug3("%s: waiting for MONITOR_ANS_JPAKE_KEY_CONFIRM", __func__); + mm_request_receive_expect(pmonitor->m_recvfd, + MONITOR_ANS_JPAKE_KEY_CONFIRM, &m); + + /* 'k' is sensitive and stays in the monitor */ + *confirm_hash = buffer_get_string(&m, confirm_hash_len); + + buffer_free(&m); +} + +int +mm_jpake_check_confirm(const BIGNUM *k, + const u_char *peer_id, u_int peer_id_len, + const u_char *sess_id, u_int sess_id_len, + const u_char *peer_confirm_hash, u_int peer_confirm_hash_len) +{ + Buffer m; + int success = 0; + + debug3("%s entering", __func__); + + buffer_init(&m); + /* k is dummy in slave, ignored */ + /* monitor knows all the ids */ + buffer_put_string(&m, peer_confirm_hash, peer_confirm_hash_len); + mm_request_send(pmonitor->m_recvfd, + MONITOR_REQ_JPAKE_CHECK_CONFIRM, &m); + + debug3("%s: waiting for MONITOR_ANS_JPAKE_CHECK_CONFIRM", __func__); + mm_request_receive_expect(pmonitor->m_recvfd, + MONITOR_ANS_JPAKE_CHECK_CONFIRM, &m); + + success = buffer_get_int(&m); + buffer_free(&m); + + debug3("%s: success = %d", __func__, success); + return success; +} +#endif /* JPAKE */ diff --git a/monitor_wrap.h b/monitor_wrap.h index 329189c2..55c4b99f 100644 --- a/monitor_wrap.h +++ b/monitor_wrap.h @@ -1,4 +1,4 @@ -/* $OpenBSD: monitor_wrap.h,v 1.20 2006/08/03 03:34:42 deraadt Exp $ */ +/* $OpenBSD: monitor_wrap.h,v 1.21 2008/11/04 08:22:13 djm Exp $ */ /* * Copyright 2002 Niels Provos <provos@citi.umich.edu> @@ -101,6 +101,26 @@ int mm_bsdauth_respond(void *, u_int, char **); int mm_skey_query(void *, char **, char **, u_int *, char ***, u_int **); int mm_skey_respond(void *, u_int, char **); +/* jpake */ +struct jpake_group; +void mm_auth2_jpake_get_pwdata(struct Authctxt *, BIGNUM **, char **, char **); +void mm_jpake_step1(struct jpake_group *, u_char **, u_int *, + BIGNUM **, BIGNUM **, BIGNUM **, BIGNUM **, + u_char **, u_int *, u_char **, u_int *); +void mm_jpake_step2(struct jpake_group *, BIGNUM *, + BIGNUM *, BIGNUM *, BIGNUM *, BIGNUM *, + const u_char *, u_int, const u_char *, u_int, + const u_char *, u_int, const u_char *, u_int, + BIGNUM **, u_char **, u_int *); +void mm_jpake_key_confirm(struct jpake_group *, BIGNUM *, BIGNUM *, + BIGNUM *, BIGNUM *, BIGNUM *, BIGNUM *, BIGNUM *, + const u_char *, u_int, const u_char *, u_int, + const u_char *, u_int, const u_char *, u_int, + BIGNUM **, u_char **, u_int *); +int mm_jpake_check_confirm(const BIGNUM *, + const u_char *, u_int, const u_char *, u_int, const u_char *, u_int); + + /* zlib allocation hooks */ void *mm_zalloc(struct mm_master *, u_int, u_int); @@ -1,4 +1,4 @@ -/* $OpenBSD: readconf.c,v 1.170 2008/11/03 02:44:41 stevesk Exp $ */ +/* $OpenBSD: readconf.c,v 1.171 2008/11/04 08:22:13 djm Exp $ */ /* * Author: Tatu Ylonen <ylo@cs.hut.fi> * Copyright (c) 1995 Tatu Ylonen <ylo@cs.hut.fi>, Espoo, Finland @@ -130,7 +130,7 @@ typedef enum { oServerAliveInterval, oServerAliveCountMax, oIdentitiesOnly, oSendEnv, oControlPath, oControlMaster, oHashKnownHosts, oTunnel, oTunnelDevice, oLocalCommand, oPermitLocalCommand, - oVisualHostKey, + oVisualHostKey, oZeroKnowledgePasswordAuthentication, oDeprecated, oUnsupported } OpCodes; @@ -228,6 +228,13 @@ static struct { { "localcommand", oLocalCommand }, { "permitlocalcommand", oPermitLocalCommand }, { "visualhostkey", oVisualHostKey }, +#ifdef JPAKE + { "zeroknowledgepasswordauthentication", + oZeroKnowledgePasswordAuthentication }, +#else + { "zeroknowledgepasswordauthentication", oUnsupported }, +#endif + { NULL, oBadOption } }; @@ -412,6 +419,10 @@ parse_flag: intptr = &options->password_authentication; goto parse_flag; + case oZeroKnowledgePasswordAuthentication: + intptr = &options->zero_knowledge_password_authentication; + goto parse_flag; + case oKbdInteractiveAuthentication: intptr = &options->kbd_interactive_authentication; goto parse_flag; @@ -1054,6 +1065,7 @@ initialize_options(Options * options) options->local_command = NULL; options->permit_local_command = -1; options->visual_host_key = -1; + options->zero_knowledge_password_authentication = -1; } /* @@ -1190,6 +1202,8 @@ fill_default_options(Options * options) options->permit_local_command = 0; if (options->visual_host_key == -1) options->visual_host_key = 0; + if (options->zero_knowledge_password_authentication == -1) + options->zero_knowledge_password_authentication = 0; /* options->local_command should not be set by default */ /* options->proxy_command should not be set by default */ /* options->user will be set in the main program if appropriate */ @@ -1,4 +1,4 @@ -/* $OpenBSD: readconf.h,v 1.75 2008/11/01 17:40:33 stevesk Exp $ */ +/* $OpenBSD: readconf.h,v 1.76 2008/11/04 08:22:13 djm Exp $ */ /* * Author: Tatu Ylonen <ylo@cs.hut.fi> @@ -49,6 +49,7 @@ typedef struct { * authentication. */ int kbd_interactive_authentication; /* Try keyboard-interactive auth. */ char *kbd_interactive_devices; /* Keyboard-interactive auth devices. */ + int zero_knowledge_password_authentication; /* Try jpake */ int batch_mode; /* Batch mode: do not ask for passwords. */ int check_host_ip; /* Also keep track of keys for IP address */ int strict_host_key_checking; /* Strict host key checking. */ diff --git a/schnorr.c b/schnorr.c new file mode 100644 index 00000000..e3abe570 --- /dev/null +++ b/schnorr.c @@ -0,0 +1,407 @@ +/* $OpenBSD: schnorr.c,v 1.1 2008/11/04 08:22:13 djm Exp $ */ +/* + * Copyright (c) 2008 Damien Miller. All rights reserved. + * + * Permission to use, copy, modify, and distribute this software for any + * purpose with or without fee is hereby granted, provided that the above + * copyright notice and this permission notice appear in all copies. + * + * THE SOFTWARE IS PROVIDED "AS IS" AND THE AUTHOR DISCLAIMS ALL WARRANTIES + * WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF + * MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR + * ANY SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES + * WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR PROFITS, WHETHER IN AN + * ACTION OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING OUT OF + * OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE. + */ + +/* + * Implementation of Schnorr signatures / zero-knowledge proofs, based on + * description in: + * + * F. Hao, P. Ryan, "Password Authenticated Key Exchange by Juggling", + * 16th Workshop on Security Protocols, Cambridge, April 2008 + * + * http://grouper.ieee.org/groups/1363/Research/contributions/hao-ryan-2008.pdf + */ + +#include "includes.h" + +#include <sys/types.h> + +#include <string.h> +#include <stdarg.h> +#include <stdio.h> + +#include <openssl/evp.h> +#include <openssl/bn.h> + +#include "xmalloc.h" +#include "buffer.h" +#include "log.h" + +#include "jpake.h" + +/* #define SCHNORR_DEBUG */ /* Privacy-violating debugging */ +/* #define SCHNORR_MAIN */ /* Include main() selftest */ + +/* XXX */ +/* Parametise signature hash? (sha256, sha1, etc.) */ +/* Signature format - include type name, hash type, group params? */ + +#ifndef SCHNORR_DEBUG +# define SCHNORR_DEBUG_BN(a) +# define SCHNORR_DEBUG_BUF(a) +#else +# define SCHNORR_DEBUG_BN(a) jpake_debug3_bn a +# define SCHNORR_DEBUG_BUF(a) jpake_debug3_buf a +#endif /* SCHNORR_DEBUG */ + +/* + * Calculate hash component of Schnorr signature H(g || g^v || g^x || id) + * using SHA1. Returns signature as bignum or NULL on error. + */ +static BIGNUM * +schnorr_hash(const BIGNUM *p, const BIGNUM *q, const BIGNUM *g, + const BIGNUM *g_v, const BIGNUM *g_x, + const u_char *id, u_int idlen) +{ + u_char *digest; + u_int digest_len; + BIGNUM *h; + EVP_MD_CTX evp_md_ctx; + Buffer b; + int success = -1; + + if ((h = BN_new()) == NULL) { + error("%s: BN_new", __func__); + return NULL; + } + + buffer_init(&b); + EVP_MD_CTX_init(&evp_md_ctx); + + /* h = H(g || g^v || g^x || id) */ + buffer_put_bignum2(&b, g); + buffer_put_bignum2(&b, g_v); + buffer_put_bignum2(&b, g_x); + buffer_put_string(&b, id, idlen); + + SCHNORR_DEBUG_BUF((buffer_ptr(&b), buffer_len(&b), + "%s: hashblob", __func__)); + if (hash_buffer(buffer_ptr(&b), buffer_len(&b), EVP_sha256(), + &digest, &digest_len) != 0) { + error("%s: hash_buffer", __func__); + goto out; + } + if (BN_bin2bn(digest, (int)digest_len, h) == NULL) { + error("%s: BN_bin2bn", __func__); + goto out; + } + success = 0; + SCHNORR_DEBUG_BN((h, "%s: h = ", __func__)); + out: + buffer_free(&b); + EVP_MD_CTX_cleanup(&evp_md_ctx); + bzero(digest, digest_len); + xfree(digest); + digest_len = 0; + if (success == 0) + return h; + BN_clear_free(h); + return NULL; +} + +/* + * Generate Schnorr signature to prove knowledge of private value 'x' used + * in public exponent g^x, under group defined by 'grp_p', 'grp_q' and 'grp_g' + * 'idlen' bytes from 'id' will be included in the signature hash as an anti- + * replay salt. + * On success, 0 is returned and *siglen bytes of signature are returned in + * *sig (caller to free). Returns -1 on failure. + */ +int +schnorr_sign(const BIGNUM *grp_p, const BIGNUM *grp_q, const BIGNUM *grp_g, + const BIGNUM *x, const BIGNUM *g_x, const u_char *id, u_int idlen, + u_char **sig, u_int *siglen) +{ + int success = -1; + Buffer b; + BIGNUM *h, *tmp, *v, *g_v, *r; + BN_CTX *bn_ctx; + + SCHNORR_DEBUG_BN((x, "%s: x = ", __func__)); + SCHNORR_DEBUG_BN((g_x, "%s: g_x = ", __func__)); + + /* Avoid degenerate cases: g^0 yields a spoofable signature */ + if (BN_cmp(g_x, BN_value_one()) <= 0) { + error("%s: g_x < 1", __func__); + return -1; + } + + h = g_v = r = tmp = v = NULL; + if ((bn_ctx = BN_CTX_new()) == NULL) { + error("%s: BN_CTX_new", __func__); + goto out; + } + if ((g_v = BN_new()) == NULL || + (r = BN_new()) == NULL || + (tmp = BN_new()) == NULL) { + error("%s: BN_new", __func__); + goto out; + } + + /* + * v must be a random element of Zq, so 1 <= v < q + * we also exclude v = 1, since g^1 looks dangerous + */ + if ((v = bn_rand_range_gt_one(grp_p)) == NULL) { + error("%s: bn_rand_range2", __func__); + goto out; + } + SCHNORR_DEBUG_BN((v, "%s: v = ", __func__)); + + /* g_v = g^v mod p */ + if (BN_mod_exp(g_v, grp_g, v, grp_p, bn_ctx) == -1) { + error("%s: BN_mod_exp (g^v mod p)", __func__); + goto out; + } + SCHNORR_DEBUG_BN((g_v, "%s: g_v = ", __func__)); + + /* h = H(g || g^v || g^x || id) */ + if ((h = schnorr_hash(grp_p, grp_q, grp_g, g_v, g_x, + id, idlen)) == NULL) { + error("%s: schnorr_hash failed", __func__); + goto out; + } + + /* r = v - xh mod q */ + if (BN_mod_mul(tmp, x, h, grp_q, bn_ctx) == -1) { + error("%s: BN_mod_mul (tmp = xv mod q)", __func__); + goto out; + } + if (BN_mod_sub(r, v, tmp, grp_q, bn_ctx) == -1) { + error("%s: BN_mod_mul (r = v - tmp)", __func__); + goto out; + } + SCHNORR_DEBUG_BN((r, "%s: r = ", __func__)); + + /* Signature is (g_v, r) */ + buffer_init(&b); + /* XXX sigtype-hash as string? */ + buffer_put_bignum2(&b, g_v); + buffer_put_bignum2(&b, r); + *siglen = buffer_len(&b); + *sig = xmalloc(*siglen); + memcpy(*sig, buffer_ptr(&b), *siglen); + SCHNORR_DEBUG_BUF((buffer_ptr(&b), buffer_len(&b), + "%s: sigblob", __func__)); + buffer_free(&b); + success = 0; + out: + BN_CTX_free(bn_ctx); + if (h != NULL) + BN_clear_free(h); + if (v != NULL) + BN_clear_free(v); + BN_clear_free(r); + BN_clear_free(g_v); + BN_clear_free(tmp); + + return success; +} + +/* + * Verify Schnorr signature 'sig' of length 'siglen' against public exponent + * g_x (g^x) under group defined by 'grp_p', 'grp_q' and 'grp_g'. + * Signature hash will be salted with 'idlen' bytes from 'id'. + * Returns -1 on failure, 0 on incorrect signature or 1 on matching signature. + */ +int +schnorr_verify(const BIGNUM *grp_p, const BIGNUM *grp_q, const BIGNUM *grp_g, + const BIGNUM *g_x, const u_char *id, u_int idlen, + const u_char *sig, u_int siglen) +{ + int success = -1; + Buffer b; + BIGNUM *g_v, *h, *r, *g_xh, *g_r, *expected; + BN_CTX *bn_ctx; + u_int rlen; + + SCHNORR_DEBUG_BN((g_x, "%s: g_x = ", __func__)); + + /* Avoid degenerate cases: g^0 yields a spoofable signature */ + if (BN_cmp(g_x, BN_value_one()) <= 0) { + error("%s: g_x < 1", __func__); + return -1; + } + + g_v = h = r = g_xh = g_r = expected = NULL; + if ((bn_ctx = BN_CTX_new()) == NULL) { + error("%s: BN_CTX_new", __func__); + goto out; + } + if ((g_v = BN_new()) == NULL || + (r = BN_new()) == NULL || + (g_xh = BN_new()) == NULL || + (g_r = BN_new()) == NULL || + (expected = BN_new()) == NULL) { + error("%s: BN_new", __func__); + goto out; + } + + /* Extract g^v and r from signature blob */ + buffer_init(&b); + buffer_append(&b, sig, siglen); + SCHNORR_DEBUG_BUF((buffer_ptr(&b), buffer_len(&b), + "%s: sigblob", __func__)); + buffer_get_bignum2(&b, g_v); + buffer_get_bignum2(&b, r); + rlen = buffer_len(&b); + buffer_free(&b); + if (rlen != 0) { + error("%s: remaining bytes in signature %d", __func__, rlen); + goto out; + } + buffer_free(&b); + SCHNORR_DEBUG_BN((g_v, "%s: g_v = ", __func__)); + SCHNORR_DEBUG_BN((r, "%s: r = ", __func__)); + + /* h = H(g || g^v || g^x || id) */ + if ((h = schnorr_hash(grp_p, grp_q, grp_g, g_v, g_x, + id, idlen)) == NULL) { + error("%s: schnorr_hash failed", __func__); + goto out; + } + + /* g_xh = (g^x)^h */ + if (BN_mod_exp(g_xh, g_x, h, grp_p, bn_ctx) == -1) { + error("%s: BN_mod_exp (g_x^h mod p)", __func__); + goto out; + } + SCHNORR_DEBUG_BN((g_xh, "%s: g_xh = ", __func__)); + + /* g_r = g^r */ + if (BN_mod_exp(g_r, grp_g, r, grp_p, bn_ctx) == -1) { + error("%s: BN_mod_exp (g_x^h mod p)", __func__); + goto out; + } + SCHNORR_DEBUG_BN((g_r, "%s: g_r = ", __func__)); + + /* expected = g^r * g_xh */ + if (BN_mod_mul(expected, g_r, g_xh, grp_p, bn_ctx) == -1) { + error("%s: BN_mod_mul (expected = g_r mod p)", __func__); + goto out; + } + SCHNORR_DEBUG_BN((expected, "%s: expected = ", __func__)); + + /* Check g_v == expected */ + success = BN_cmp(expected, g_v) == 0; + out: + BN_CTX_free(bn_ctx); + if (h != NULL) + BN_clear_free(h); + BN_clear_free(g_v); + BN_clear_free(r); + BN_clear_free(g_xh); + BN_clear_free(g_r); + BN_clear_free(expected); + return success; +} + +#ifdef SCHNORR_MAIN +static void +schnorr_selftest_one(const BIGNUM *grp_p, const BIGNUM *grp_q, + const BIGNUM *grp_g, const BIGNUM *x) +{ + BIGNUM *g_x; + u_char *sig; + u_int siglen; + BN_CTX *bn_ctx; + + if ((bn_ctx = BN_CTX_new()) == NULL) + fatal("%s: BN_CTX_new", __func__); + if ((g_x = BN_new()) == NULL) + fatal("%s: BN_new", __func__); + + if (BN_mod_exp(g_x, grp_g, x, grp_p, bn_ctx) == -1) + fatal("%s: g_x", __func__); + if (schnorr_sign(grp_p, grp_q, grp_g, x, g_x, "junk", 4, &sig, &siglen)) + fatal("%s: schnorr_sign", __func__); + if (schnorr_verify(grp_p, grp_q, grp_g, g_x, "junk", 4, + sig, siglen) != 1) + fatal("%s: verify fail", __func__); + if (schnorr_verify(grp_p, grp_q, grp_g, g_x, "JUNK", 4, + sig, siglen) != 0) + fatal("%s: verify should have failed (bad ID)", __func__); + sig[4] ^= 1; + if (schnorr_verify(grp_p, grp_q, grp_g, g_x, "junk", 4, + sig, siglen) != 0) + fatal("%s: verify should have failed (bit error)", __func__); + xfree(sig); + BN_free(g_x); + BN_CTX_free(bn_ctx); +} + +static void +schnorr_selftest(void) +{ + BIGNUM *x; + struct jpake_group *grp; + u_int i; + char *hh; + + grp = jpake_default_group(); + if ((x = BN_new()) == NULL) + fatal("%s: BN_new", __func__); + SCHNORR_DEBUG_BN((grp->p, "%s: grp->p = ", __func__)); + SCHNORR_DEBUG_BN((grp->q, "%s: grp->q = ", __func__)); + SCHNORR_DEBUG_BN((grp->g, "%s: grp->g = ", __func__)); + + /* [1, 20) */ + for (i = 1; i < 20; i++) { + printf("x = %u\n", i); + fflush(stdout); + if (BN_set_word(x, i) != 1) + fatal("%s: set x word", __func__); + schnorr_selftest_one(grp->p, grp->q, grp->g, x); + } + + /* 100 x random [0, p) */ + for (i = 0; i < 100; i++) { + if (BN_rand_range(x, grp->p) != 1) + fatal("%s: BN_rand_range", __func__); + hh = BN_bn2hex(x); + printf("x = (random) 0x%s\n", hh); + free(hh); + fflush(stdout); + schnorr_selftest_one(grp->p, grp->q, grp->g, x); + } + + /* [q-20, q) */ + if (BN_set_word(x, 20) != 1) + fatal("%s: BN_set_word (x = 20)", __func__); + if (BN_sub(x, grp->q, x) != 1) + fatal("%s: BN_sub (q - x)", __func__); + for (i = 0; i < 19; i++) { + hh = BN_bn2hex(x); + printf("x = (q - %d) 0x%s\n", 20 - i, hh); + free(hh); + fflush(stdout); + schnorr_selftest_one(grp->p, grp->q, grp->g, x); + if (BN_add(x, x, BN_value_one()) != 1) + fatal("%s: BN_add (x + 1)", __func__); + } + BN_free(x); +} + +int +main(int argc, char **argv) +{ + log_init(argv[0], SYSLOG_LEVEL_DEBUG3, SYSLOG_FACILITY_USER, 1); + + schnorr_selftest(); + return 0; +} +#endif + @@ -1,4 +1,4 @@ -/* $OpenBSD: servconf.c,v 1.189 2008/11/03 08:59:41 djm Exp $ */ +/* $OpenBSD: servconf.c,v 1.190 2008/11/04 08:22:13 djm Exp $ */ /* * Copyright (c) 1995 Tatu Ylonen <ylo@cs.hut.fi>, Espoo, Finland * All rights reserved @@ -127,6 +127,7 @@ initialize_server_options(ServerOptions *options) options->num_permitted_opens = -1; options->adm_forced_command = NULL; options->chroot_directory = NULL; + options->zero_knowledge_password_authentication = -1; } void @@ -258,6 +259,8 @@ fill_default_server_options(ServerOptions *options) options->authorized_keys_file = _PATH_SSH_USER_PERMITTED_KEYS; if (options->permit_tun == -1) options->permit_tun = SSH_TUNMODE_NO; + if (options->zero_knowledge_password_authentication == -1) + options->zero_knowledge_password_authentication = 0; /* Turn privilege separation on by default */ if (use_privsep == -1) @@ -302,6 +305,7 @@ typedef enum { sGssAuthentication, sGssCleanupCreds, sAcceptEnv, sPermitTunnel, sMatch, sPermitOpen, sForceCommand, sChrootDirectory, sUsePrivilegeSeparation, sAllowAgentForwarding, + sZeroKnowledgePasswordAuthentication, sDeprecated, sUnsupported } ServerOpCodes; @@ -368,6 +372,11 @@ static struct { { "kbdinteractiveauthentication", sKbdInteractiveAuthentication, SSHCFG_ALL }, { "challengeresponseauthentication", sChallengeResponseAuthentication, SSHCFG_GLOBAL }, { "skeyauthentication", sChallengeResponseAuthentication, SSHCFG_GLOBAL }, /* alias */ +#ifdef JPAKE + { "zeroknowledgepasswordauthentication", sZeroKnowledgePasswordAuthentication, SSHCFG_ALL }, +#else + { "zeroknowledgepasswordauthentication", sUnsupported, SSHCFG_ALL }, +#endif { "checkmail", sDeprecated, SSHCFG_GLOBAL }, { "listenaddress", sListenAddress, SSHCFG_GLOBAL }, { "addressfamily", sAddressFamily, SSHCFG_GLOBAL }, @@ -890,6 +899,10 @@ process_server_config_line(ServerOptions *options, char *line, intptr = &options->password_authentication; goto parse_flag; + case sZeroKnowledgePasswordAuthentication: + intptr = &options->zero_knowledge_password_authentication; + goto parse_flag; + case sKbdInteractiveAuthentication: intptr = &options->kbd_interactive_authentication; goto parse_flag; @@ -1377,6 +1390,7 @@ copy_set_server_options(ServerOptions *dst, ServerOptions *src, int preauth) M_CP_INTOPT(kerberos_authentication); M_CP_INTOPT(hostbased_authentication); M_CP_INTOPT(kbd_interactive_authentication); + M_CP_INTOPT(zero_knowledge_password_authentication); M_CP_INTOPT(permit_root_login); M_CP_INTOPT(permit_empty_passwd); @@ -1579,6 +1593,10 @@ dump_config(ServerOptions *o) dump_cfg_fmtint(sGssAuthentication, o->gss_authentication); dump_cfg_fmtint(sGssCleanupCreds, o->gss_cleanup_creds); #endif +#ifdef JPAKE + dump_cfg_fmtint(sZeroKnowledgePasswordAuthentication, + o->zero_knowledge_password_authentication); +#endif dump_cfg_fmtint(sPasswordAuthentication, o->password_authentication); dump_cfg_fmtint(sKbdInteractiveAuthentication, o->kbd_interactive_authentication); @@ -1,4 +1,4 @@ -/* $OpenBSD: servconf.h,v 1.85 2008/06/10 04:50:25 dtucker Exp $ */ +/* $OpenBSD: servconf.h,v 1.86 2008/11/04 08:22:13 djm Exp $ */ /* * Author: Tatu Ylonen <ylo@cs.hut.fi> @@ -96,6 +96,8 @@ typedef struct { * authentication. */ int kbd_interactive_authentication; /* If true, permit */ int challenge_response_authentication; + int zero_knowledge_password_authentication; + /* If true, permit jpake auth */ int permit_empty_passwd; /* If false, do not permit empty * passwords. */ int permit_user_env; /* If true, read ~/.ssh/environment */ @@ -1,4 +1,4 @@ -/* $OpenBSD: ssh2.h,v 1.10 2006/03/25 22:22:43 djm Exp $ */ +/* $OpenBSD: ssh2.h,v 1.11 2008/11/04 08:22:13 djm Exp $ */ /* * Copyright (c) 2000 Markus Friedl. All rights reserved. @@ -111,6 +111,12 @@ #define SSH2_MSG_USERAUTH_PASSWD_CHANGEREQ 60 #define SSH2_MSG_USERAUTH_INFO_REQUEST 60 #define SSH2_MSG_USERAUTH_INFO_RESPONSE 61 +#define SSH2_MSG_USERAUTH_JPAKE_CLIENT_STEP1 60 +#define SSH2_MSG_USERAUTH_JPAKE_SERVER_STEP1 61 +#define SSH2_MSG_USERAUTH_JPAKE_CLIENT_STEP2 62 +#define SSH2_MSG_USERAUTH_JPAKE_SERVER_STEP2 63 +#define SSH2_MSG_USERAUTH_JPAKE_CLIENT_CONFIRM 64 +#define SSH2_MSG_USERAUTH_JPAKE_SERVER_CONFIRM 65 /* connection protocol: generic */ @@ -159,3 +165,4 @@ #define SSH2_OPEN_RESOURCE_SHORTAGE 4 #define SSH2_EXTENDED_DATA_STDERR 1 + diff --git a/ssh_config.5 b/ssh_config.5 index 254940ef..abc3b0b1 100644 --- a/ssh_config.5 +++ b/ssh_config.5 @@ -34,8 +34,8 @@ .\" (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF .\" THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE. .\" -.\" $OpenBSD: ssh_config.5,v 1.114 2008/10/17 18:36:24 stevesk Exp $ -.Dd $Mdocdate: October 17 2008 $ +.\" $OpenBSD: ssh_config.5,v 1.115 2008/11/04 08:22:13 djm Exp $ +.Dd $Mdocdate: November 4 2008 $ .Dt SSH_CONFIG 5 .Os .Sh NAME @@ -1079,6 +1079,17 @@ Specifies the full pathname of the program. The default is .Pa /usr/X11R6/bin/xauth . +.It Cm ZeroKnowledgePasswordAuthentication +Specifies whether to use zero knowledge password authentication. +This authentication method avoids exposure of password to untrusted +hosts. +The argument to this keyword must be +.Dq yes +or +.Dq no . +The default is currently +.Dq no +as this method is considered experimental. .El .Sh PATTERNS A diff --git a/sshconnect2.c b/sshconnect2.c index 7d0c5e82..a762eec3 100644 --- a/sshconnect2.c +++ b/sshconnect2.c @@ -1,6 +1,7 @@ -/* $OpenBSD: sshconnect2.c,v 1.169 2008/11/01 04:50:08 djm Exp $ */ +/* $OpenBSD: sshconnect2.c,v 1.170 2008/11/04 08:22:13 djm Exp $ */ /* * Copyright (c) 2000 Markus Friedl. All rights reserved. + * Copyright (c) 2008 Damien Miller. All rights reserved. * * Redistribution and use in source and binary forms, with or without * modification, are permitted provided that the following conditions @@ -67,6 +68,7 @@ #include "msg.h" #include "pathnames.h" #include "uidswap.h" +#include "jpake.h" #ifdef GSSAPI #include "ssh-gss.h" @@ -201,6 +203,7 @@ struct Authctxt { struct Authmethod { char *name; /* string to compare against server's list */ int (*userauth)(Authctxt *authctxt); + void (*cleanup)(Authctxt *authctxt); int *enabled; /* flag in option struct that enables method */ int *batch_flag; /* flag in option struct that disables method */ }; @@ -212,12 +215,18 @@ void input_userauth_error(int, u_int32_t, void *); void input_userauth_info_req(int, u_int32_t, void *); void input_userauth_pk_ok(int, u_int32_t, void *); void input_userauth_passwd_changereq(int, u_int32_t, void *); +void input_userauth_jpake_server_step1(int, u_int32_t, void *); +void input_userauth_jpake_server_step2(int, u_int32_t, void *); +void input_userauth_jpake_server_confirm(int, u_int32_t, void *); int userauth_none(Authctxt *); int userauth_pubkey(Authctxt *); int userauth_passwd(Authctxt *); int userauth_kbdint(Authctxt *); int userauth_hostbased(Authctxt *); +int userauth_jpake(Authctxt *); + +void userauth_jpake_cleanup(Authctxt *); #ifdef GSSAPI int userauth_gssapi(Authctxt *authctxt); @@ -243,30 +252,43 @@ Authmethod authmethods[] = { #ifdef GSSAPI {"gssapi-with-mic", userauth_gssapi, + NULL, &options.gss_authentication, NULL}, #endif {"hostbased", userauth_hostbased, + NULL, &options.hostbased_authentication, NULL}, {"publickey", userauth_pubkey, + NULL, &options.pubkey_authentication, NULL}, +#ifdef JPAKE + {"jpake-01@openssh.com", + userauth_jpake, + userauth_jpake_cleanup, + &options.zero_knowledge_password_authentication, + &options.batch_mode}, +#endif {"keyboard-interactive", userauth_kbdint, + NULL, &options.kbd_interactive_authentication, &options.batch_mode}, {"password", userauth_passwd, + NULL, &options.password_authentication, &options.batch_mode}, {"none", userauth_none, NULL, + NULL, NULL}, - {NULL, NULL, NULL, NULL} + {NULL, NULL, NULL, NULL, NULL} }; void @@ -334,6 +356,9 @@ ssh_userauth2(const char *local_user, const char *server_user, char *host, void userauth(Authctxt *authctxt, char *authlist) { + if (authctxt->method != NULL && authctxt->method->cleanup != NULL) + authctxt->method->cleanup(authctxt); + if (authctxt->methoddata) { xfree(authctxt->methoddata); authctxt->methoddata = NULL; @@ -851,6 +876,209 @@ input_userauth_passwd_changereq(int type, u_int32_t seqnr, void *ctxt) &input_userauth_passwd_changereq); } +#ifdef JPAKE +static char * +pw_encrypt(const char *password, const char *crypt_scheme, const char *salt) +{ + /* OpenBSD crypt(3) handles all of these */ + if (strcmp(crypt_scheme, "crypt") == 0 || + strcmp(crypt_scheme, "bcrypt") == 0 || + strcmp(crypt_scheme, "md5crypt") == 0 || + strcmp(crypt_scheme, "crypt-extended") == 0) + return xstrdup(crypt(password, salt)); + error("%s: unsupported password encryption scheme \"%.100s\"", + __func__, crypt_scheme); + return NULL; +} + +static BIGNUM * +jpake_password_to_secret(Authctxt *authctxt, const char *crypt_scheme, + const char *salt) +{ + char prompt[256], *password, *crypted; + u_char *secret; + u_int secret_len; + BIGNUM *ret; + + snprintf(prompt, sizeof(prompt), "%.30s@%.128s's password (JPAKE): ", + authctxt->server_user, authctxt->host); + password = read_passphrase(prompt, 0); + + if ((crypted = pw_encrypt(password, crypt_scheme, salt)) == NULL) { + logit("Disabling %s authentication", authctxt->method->name); + authctxt->method->enabled = NULL; + /* Continue with an empty password to fail gracefully */ + crypted = xstrdup(""); + } + +#ifdef JPAKE_DEBUG + debug3("%s: salt = %s", __func__, salt); + debug3("%s: scheme = %s", __func__, crypt_scheme); + debug3("%s: crypted = %s", __func__, crypted); +#endif + + if (hash_buffer(crypted, strlen(crypted), EVP_sha256(), + &secret, &secret_len) != 0) + fatal("%s: hash_buffer", __func__); + + bzero(password, strlen(password)); + bzero(crypted, strlen(crypted)); + xfree(password); + xfree(crypted); + + if ((ret = BN_bin2bn(secret, secret_len, NULL)) == NULL) + fatal("%s: BN_bin2bn (secret)", __func__); + bzero(secret, secret_len); + xfree(secret); + + return ret; +} + +/* ARGSUSED */ +void +input_userauth_jpake_server_step1(int type, u_int32_t seq, void *ctxt) +{ + Authctxt *authctxt = ctxt; + struct jpake_ctx *pctx = authctxt->methoddata; + u_char *x3_proof, *x4_proof, *x2_s_proof; + u_int x3_proof_len, x4_proof_len, x2_s_proof_len; + char *crypt_scheme, *salt; + + /* Disable this message */ + dispatch_set(SSH2_MSG_USERAUTH_JPAKE_SERVER_STEP1, NULL); + + if ((pctx->g_x3 = BN_new()) == NULL || + (pctx->g_x4 = BN_new()) == NULL) + fatal("%s: BN_new", __func__); + + /* Fetch step 1 values */ + crypt_scheme = packet_get_string(NULL); + salt = packet_get_string(NULL); + pctx->server_id = packet_get_string(&pctx->server_id_len); + packet_get_bignum2(pctx->g_x3); + packet_get_bignum2(pctx->g_x4); + x3_proof = packet_get_string(&x3_proof_len); + x4_proof = packet_get_string(&x4_proof_len); + packet_check_eom(); + + JPAKE_DEBUG_CTX((pctx, "step 1 received in %s", __func__)); + + /* Obtain password and derive secret */ + pctx->s = jpake_password_to_secret(authctxt, crypt_scheme, salt); + bzero(crypt_scheme, strlen(crypt_scheme)); + bzero(salt, strlen(salt)); + xfree(crypt_scheme); + xfree(salt); + JPAKE_DEBUG_BN((pctx->s, "%s: s = ", __func__)); + + /* Calculate step 2 values */ + jpake_step2(pctx->grp, pctx->s, pctx->g_x1, + pctx->g_x3, pctx->g_x4, pctx->x2, + pctx->server_id, pctx->server_id_len, + pctx->client_id, pctx->client_id_len, + x3_proof, x3_proof_len, + x4_proof, x4_proof_len, + &pctx->a, + &x2_s_proof, &x2_s_proof_len); + + bzero(x3_proof, x3_proof_len); + bzero(x4_proof, x4_proof_len); + xfree(x3_proof); + xfree(x4_proof); + + JPAKE_DEBUG_CTX((pctx, "step 2 sending in %s", __func__)); + + /* Send values for step 2 */ + packet_start(SSH2_MSG_USERAUTH_JPAKE_CLIENT_STEP2); + packet_put_bignum2(pctx->a); + packet_put_string(x2_s_proof, x2_s_proof_len); + packet_send(); + + bzero(x2_s_proof, x2_s_proof_len); + xfree(x2_s_proof); + + /* Expect step 2 packet from peer */ + dispatch_set(SSH2_MSG_USERAUTH_JPAKE_SERVER_STEP2, + input_userauth_jpake_server_step2); +} + +/* ARGSUSED */ +void +input_userauth_jpake_server_step2(int type, u_int32_t seq, void *ctxt) +{ + Authctxt *authctxt = ctxt; + struct jpake_ctx *pctx = authctxt->methoddata; + u_char *x4_s_proof; + u_int x4_s_proof_len; + + /* Disable this message */ + dispatch_set(SSH2_MSG_USERAUTH_JPAKE_SERVER_STEP2, NULL); + + if ((pctx->b = BN_new()) == NULL) + fatal("%s: BN_new", __func__); + + /* Fetch step 2 values */ + packet_get_bignum2(pctx->b); + x4_s_proof = packet_get_string(&x4_s_proof_len); + packet_check_eom(); + + JPAKE_DEBUG_CTX((pctx, "step 2 received in %s", __func__)); + + /* Derive shared key and calculate confirmation hash */ + jpake_key_confirm(pctx->grp, pctx->s, pctx->b, + pctx->x2, pctx->g_x1, pctx->g_x2, pctx->g_x3, pctx->g_x4, + pctx->client_id, pctx->client_id_len, + pctx->server_id, pctx->server_id_len, + session_id2, session_id2_len, + x4_s_proof, x4_s_proof_len, + &pctx->k, + &pctx->h_k_cid_sessid, &pctx->h_k_cid_sessid_len); + + bzero(x4_s_proof, x4_s_proof_len); + xfree(x4_s_proof); + + JPAKE_DEBUG_CTX((pctx, "confirm sending in %s", __func__)); + + /* Send key confirmation proof */ + packet_start(SSH2_MSG_USERAUTH_JPAKE_CLIENT_CONFIRM); + packet_put_string(pctx->h_k_cid_sessid, pctx->h_k_cid_sessid_len); + packet_send(); + + /* Expect confirmation from peer */ + dispatch_set(SSH2_MSG_USERAUTH_JPAKE_SERVER_CONFIRM, + input_userauth_jpake_server_confirm); +} + +/* ARGSUSED */ +void +input_userauth_jpake_server_confirm(int type, u_int32_t seq, void *ctxt) +{ + Authctxt *authctxt = ctxt; + struct jpake_ctx *pctx = authctxt->methoddata; + + /* Disable this message */ + dispatch_set(SSH2_MSG_USERAUTH_JPAKE_SERVER_CONFIRM, NULL); + + pctx->h_k_sid_sessid = packet_get_string(&pctx->h_k_sid_sessid_len); + packet_check_eom(); + + JPAKE_DEBUG_CTX((pctx, "confirm received in %s", __func__)); + + /* Verify expected confirmation hash */ + if (jpake_check_confirm(pctx->k, + pctx->server_id, pctx->server_id_len, + session_id2, session_id2_len, + pctx->h_k_sid_sessid, pctx->h_k_sid_sessid_len) == 1) + debug("%s: %s success", __func__, authctxt->method->name); + else { + debug("%s: confirmation mismatch", __func__); + /* XXX stash this so if auth succeeds then we can warn/kill */ + } + + userauth_jpake_cleanup(authctxt); +} +#endif /* JPAKE */ + static int identity_sign(Identity *id, u_char **sigp, u_int *lenp, u_char *data, u_int datalen) @@ -1425,6 +1653,76 @@ userauth_hostbased(Authctxt *authctxt) return 1; } +#ifdef JPAKE +int +userauth_jpake(Authctxt *authctxt) +{ + struct jpake_ctx *pctx; + u_char *x1_proof, *x2_proof; + u_int x1_proof_len, x2_proof_len; + static int attempt = 0; /* XXX share with userauth_password's? */ + + if (attempt++ >= options.number_of_password_prompts) + return 0; + if (attempt != 1) + error("Permission denied, please try again."); + + if (authctxt->methoddata != NULL) + fatal("%s: authctxt->methoddata already set (%p)", + __func__, authctxt->methoddata); + + authctxt->methoddata = pctx = jpake_new(); + + /* + * Send request immediately, to get the protocol going while + * we do the initial computations. + */ + packet_start(SSH2_MSG_USERAUTH_REQUEST); + packet_put_cstring(authctxt->server_user); + packet_put_cstring(authctxt->service); + packet_put_cstring(authctxt->method->name); + packet_send(); + packet_write_wait(); + + jpake_step1(pctx->grp, + &pctx->client_id, &pctx->client_id_len, + &pctx->x1, &pctx->x2, &pctx->g_x1, &pctx->g_x2, + &x1_proof, &x1_proof_len, + &x2_proof, &x2_proof_len); + + JPAKE_DEBUG_CTX((pctx, "step 1 sending in %s", __func__)); + + packet_start(SSH2_MSG_USERAUTH_JPAKE_CLIENT_STEP1); + packet_put_string(pctx->client_id, pctx->client_id_len); + packet_put_bignum2(pctx->g_x1); + packet_put_bignum2(pctx->g_x2); + packet_put_string(x1_proof, x1_proof_len); + packet_put_string(x2_proof, x2_proof_len); + packet_send(); + + bzero(x1_proof, x1_proof_len); + bzero(x2_proof, x2_proof_len); + xfree(x1_proof); + xfree(x2_proof); + + /* Expect step 1 packet from peer */ + dispatch_set(SSH2_MSG_USERAUTH_JPAKE_SERVER_STEP1, + input_userauth_jpake_server_step1); + + return 1; +} + +void +userauth_jpake_cleanup(Authctxt *authctxt) +{ + debug3("%s: clean up", __func__); + if (authctxt->methoddata != NULL) { + jpake_free(authctxt->methoddata); + authctxt->methoddata = NULL; + } +} +#endif /* JPAKE */ + /* find auth method */ /* @@ -1526,3 +1824,4 @@ authmethods_get(void) buffer_free(&b); return list; } + diff --git a/sshd_config.5 b/sshd_config.5 index 06fe5fd3..a4a4be6e 100644 --- a/sshd_config.5 +++ b/sshd_config.5 @@ -34,8 +34,8 @@ .\" (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF .\" THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE. .\" -.\" $OpenBSD: sshd_config.5,v 1.97 2008/10/09 03:50:54 djm Exp $ -.Dd $Mdocdate: October 9 2008 $ +.\" $OpenBSD: sshd_config.5,v 1.98 2008/11/04 08:22:13 djm Exp $ +.Dd $Mdocdate: November 4 2008 $ .Dt SSHD_CONFIG 5 .Os .Sh NAME @@ -612,8 +612,9 @@ Available keywords are .Cm RSAAuthentication , .Cm X11DisplayOffset , .Cm X11Forwarding , +.Cm X11UseLocalHost , and -.Cm X11UseLocalHost . +.Cm ZeroKnowledgePasswordAuthentication . .It Cm MaxAuthTries Specifies the maximum number of authentication attempts permitted per connection. @@ -1004,6 +1005,17 @@ Specifies the full pathname of the program. The default is .Pa /usr/X11R6/bin/xauth . +.It Cm ZeroKnowledgePasswordAuthentication +Specifies whether to use zero knowledge password authentication. +This authentication method avoids exposure of password to untrusted +hosts. +The argument to this keyword must be +.Dq yes +or +.Dq no . +The default is currently +.Dq no +as this method is considered experimental. .El .Sh TIME FORMATS .Xr sshd 8 |